[From the U.S. Government Printing Office, www.gpo.gov]






                                                                                                   OCS Study
                                                                                                   MMS 99-0054


               Northeastern Gulf of Mexico
               Chemical Oceanography and
               Hydrography Study

               Annual Report: Year 2





















             GC
             111.2
             .N6
             1999




                            UIS. Dectment of the Interior
                            Minerals anawment Service
                AWGulf of Mexico             S Region







                                                                                                  OCS Study
                                                                                                  MMS 99-0054


              Northeastern Gulf of Mexico
              Chemical Oceari.Oaraphyand
              Hydrography Study.,,,

              Annual Report: Year 2






              Edilo,s


              Ann E. Jochens
              Worth D. Nowlin, Jr.










              Prepared under MMS Contract
              1435-01-97-CT-30851
              by
              Texas A&M University
              Department of Oceanography
              College Station, Texas 77843-3146










        j     Published by

              U.S. Department of the Interior
              Minerals Management Service                                                      New Orleans
              Gulf of Mexico OCS Region                                                        September 1999














                                     US Department of Commerce
                                 NOAA Coaital Services Center Library
                                      2234 South Hobson Avenue
                                      Charleston, SC 29405-2413













                                                          DISCLAIMER



                   This report has been prepared under contract between the Minerals Management Service (MMS)
                   and the Texas A&M Research Foundation. This report has been technically reviewed by the
                   MMS, and it has been approved for publication. Approval does not signify that the contents
                   necessarily reflect the views and policies of the MMS, nor does mention of trade names or
                   commercial products constitute endorsement or recommendation for use-. It is, however, exempt
                   from review and compliance with the MMS editorial standards.






                                                    REPORT AVAILABILITY


                   Extra copies of this report may be obtained from the Public Information Office (Mail Stop
                   5034) at the following address:

                                                US Department of the Interior
                                                Minerals Management Service
                                                Gulf of Mexico OCS Region
                                                Public Information Office (MS 5034)
                                                1201 Elmwood Park Boulevard
                                                New Orleans, Louisiana 70123-2394

                                                Telephone: (504) 736-2519 or
                                                            1-800-200-GULF




                                                            CITATION


                   Suggested citation:

                   Jochens, A.E. and W.D. Nowlin, Jr., eds. 1999. Northeastern Gulf of Mexico Chemical
                       Oceanography and Hydrography Study: Year 2 -Annual Report. OCS Study MMS 99-0054,
                       U.S. Dept. ofthe Interior, Minerals Management Service, Gulf ofMexico OCS Region, New
                       Orleans, LA. 123 pp.















                                                                                                                  v


                                                     ACKNOWLEDGMENTS




                   This report would not have been possible without the contributions of a large number of people.
                   Each NEGYOM-COH principal investigator (PI) contributed portions of the text, many
                   participated in the cruises and in data reduction and processing. The principal investigators,
                   their affiliations, and their tasks are:

                     Worth D. Nowlin, Jr.       TAMU             Program Nlanager, PI for Task 3
                     Ann E. Jochens             TAMU             Deputy Program Manager, PI for Program
                                                                 Management and Task 2
                     Douglas C. Biggs           TAMU             Co-PI for Task I
                     Norman L. Guinasso, Jr.    GERG/TAMU        Co-PI for Task I
                     Matthew K. Howard          TAMU             Co-PI for Task 2
                     M. C. Kennicutt II         GERG/TAMU        Co-PI for Tasks 1 and 3
                     Robert 0. Reid             TAMU             Co-PI for Task 3


                   Additionally, Dr. Steven R Dil\4arco, Dr. Yaorong Qian, and Ms. Christina Bernal contributed
                   to the authorship of this report.

                   To all who participated on the three NEGOM-COH cruises (N3, N4, and N5), both ship's crew
                   and scientific teams, we extend our great appreciation. We also thank the voluntary
                   contributions of the scientists and students at Louisiana State University (LSU), Texas A&M
                   University-Galveston (TAMUG), University of Dallas (UD), University of Colorado (CU),
                   University of South Florida (USF), University of Virginia (UV), University of Wisconsin (UW),
                   as well as Texas A&M University (TAMU) who participated in these cruises. The science crew
                   members , affiliations, and cruises are listed below.

                           Trent Apple (TAM[U; N5)
                           Christina Bernal (TAMU; N3, N4, N5)
                           Dr. Doug Biggs (TAMU; N3, N4, N5)
                           Ken Bottom (TAM[U; N3, N4, N5)
                           Cheryl Burden (TAMU; N3, N4)
                           Paul Clark (TAMU; N3, N4, N5)
                           Dr. Steve DiMarco (TAMU; N3, N4)
                           Dr. Sasha Drobyshevski (TAMUG; N3)
                           Gaston Gonzales (TAM[U; N3, N4, N5)
                           Dennis Guffy (TAM[U; N3, N4, N5)
                           Mike Fredericks (TAM[U; N3, N4, N5)
                           Dr. Caesar Fuentes-Yaco (USF; N4)
                           Glenn Gailey (TAMU; N5)
                           Nfichael Goldstein (TAMU; N3)











                vi

                       Billy Green (TAMU; N3, N4, N5)
                       Dr. Norm Guinasso (TAMU; N3, N4, N5)
                       Nancy Hess (UW; N3)
                       Chuanmin Hu (USF; N3)
                       Alexey Ivanov (TAW; N5)
                       Dr. Ann Jochens (TAMU; N5)
                       Daniel Kim (TAMU; N3)
                       Rob Masserini (USF; N4)
                       Bisman Nababan (USF; N5)
                       Denis Nadeau (USF; N3)
                       Kristin Nygaard (TAMUG; N4)
                       Joel Ortega (TAMUG; N4, N5)
                       Matt Page (TAMU; N4)
                       David Palandro (USF; N5)
                       Erik Quiroz (TAMU; N3, N5)
                       Patrick Ressler (TAMU; N4)
                       Josh Rigler (CU; N3)
                       Patrick Roddy (UD; N5)
                       Rebecca Scott (TAMU; N3)
                       Michael Seymour (LSU; N3)
                       Todd Speakman (TAMUG; N4)
                       Joe Vanderbloemen (USF; N4)
                       John Walpert (TAMU; N4, N5)
                       Elise Waltman (TAMU; N5)
                       Ou Wang (TAMU; N5)
                       Eddie Webb (TAMU; N3, N4, N5)
                       Maureen Whittaker (TAMUG; N5)
                       Pete Yanik (LTV; N3)
                       Elizabeth Zuniga (TAMUG; N4)

                Finally, thanks go to those who helped prepare equipment and process the data on shore,
                including many named above, Bob Albers, Woody Lee, Gary Wolff, and Xiang-Dong Xia.

                                                                            Ann E. Jochens.
                                                                            Worth D. Nowlin, Jr.











                                                                                                                  -vii


                                                             ABSTRACT



                    The Northeastern Gulf of Mexico Physical Oceanography Program (NEGOM) is supported by
                    the Minerals Management Service (MMS) of the U. S. Department of the Interior. Through a
                    contract between MMS and the Texas A&M Research Foundation@ several components of the
                    Texas A&M University System are conducting the Chemical Oceanography and Hydrography
                    study of NEGOM (NEGOM-COH). This report covers activities from July 1998 through June
                    1999. Data were collected from hydrographic and acoustic Doppler current profiler (ADCP)
                    surveys conducted in the Gulf of Mexico over the continental shelf and upper slope between the
                    Mississippi River Delta and Tampa Bay in water depths of 10 to 1000 in. Additionally,
                    historical and concurrent data from other programs in this region were collected.

                    Three hydrographic/ADCP surveys, N3, N4, and N5, were conducted with 98, 98, and 102
                    hydrographic sampling stations and 10 1, 112, and 96 expendable bathythermograph stations on
                    respective cruises. Each survey also included continuous ADCP measurements along the cruise
                    track. At each hydrographic sampling station continuous profiles were made of conductivity,
                    temperature, pressure, downwelling iffadiance, fluorescence, and light transmission. Up to
                    twelve water samples were taken at each station and analyzed for dissolved oxygen and six
                    nutrients: nitrate, nitrite, phosphate, silicate, ammonium, and urea. At approximately 60
                    stations on each cruise, water samples were filtered and analyzed for phytoplankton pigments
                    at the surface, from the chlorophyll maximum determined from fluorescence, and from the low
                    light regime immediately below the maximum. Pigments were determined using high
                    performance liquid chromatography. At about 60 stations on each cruise, water samples were
                    filtered and analyzed for particulate matter concentrations at surface, middle, and bottom water
                    depths and for particulate organic carbon and particulate organic nitrogen concentrations at
                    surface and bottom water depths. Bottle salinity was measured routinely at the shallowest and
                    deepest stations on each cross-shelf line. The instrumentation as well as calibration and
                    sampling procedures are described in this report. The collected data were subjected to stringent
                    quality assurance/quality control procedures.

                    Selected preliminary results are presented from the first four cruises in November 1997, May
                    1998, July/August 1998, and November 1998. Included is a description of forcing functions at
                    the times of the cruises: winds, river discharge, and offshelf eddies. The general distributions
                    of temperature, salinity, dissolved oxygen, nutrients, particulates, and pigments are discussed.
                    These distributions evidenced the influence of river discharges in the form of enhanced nutrient
                    concentrations and particulate loadings, and higher chlorophyll a concentrations near ri'verine
                    sources. Nutrients were found to be positively correlated with each other and negatively
                    correlated with chlorophyll a and oxygen. Chlorophyll a was positively correlated with oxygen
                    and particulate matter concentrations.











                                                                                                                       ix


                                                         TABLE OF CONTENTS



                                                                                                                   PAGE
                    ACKNOWLEDGMENTS                ..................................................                    v
                    ABSTRACT       ............................................................                        vii
                    LIST OF FIGURES        ....................................... ............                  ...   xi
                    LIST OF TABLES        .......................................................                     xiii
                    ACRONYMS AND ABBREVIATIONS                    ......................................               xv
                    I EXECUTIVE SUMMARY                   .............................................                  I
                          1.1      Introduction   ...................................................                    1
                          1.2      Field Data   ...................................................                      2
                          1.3      Technical Discussion     ...........................................                  2
                                   1.3.1 Forcing Functions      ........................................                 2
                                   1.3.2 Integration of Water Column Chemistry                                           4
                    2     INTRODUCTION          ....................................................                     7
                          2.1      Overview of Cruise Schedule and Nomenclature         ......................           7
                          2.2      Programmatic Changes       ..........................................                 7
                          2.3      Report Organization     ............................................                  9
                    3    DATA ACQUISITION             ................................................                 11
                          3.1      General Description of Surveys      ...................................             I I
                                   3. 1.1 Cruise N3    ..............................................                  12
                                   3.1.2 Cruise N4     ..............................................                  21
                                   3.1.3 Cruise N5     ..............................................                  31
                          3.2      Instrumentation, Calibration, and Sampling Procedures        ................       41
                                   3.2.1  Continuous Profiles     .......................................              41
                                   3.2.2  Discrete Measurements       ....................................             42
                                   3.2.3  Acoustic Doppler Current Profiler Measurements          ...............      44
                                   3.2.4  )MT Measurements         ......................................              46
                                   3.2.5  Underway Measurements         ...................................            47
                          3.3      Summary of Field Data Collected      ..................................             47
                          3.4      Summary of Historical and Concurrent Data Assembly          .................       50
                    4    DATA QUALITY ASSURANCE AND CONTROL                         .........................          51
                          4.1      Continuous Profile Data     .........................................               51
                          4.2      Discrete Measurements: Nutrients, Oxygen, and Salinity         ...............      51
                          4.3      Acoustic Doppler Current Profiler Measurements         .....................        51
                                   4.3.1 Standard ADCP Processing          ................................            51
                                   4.3.2 New Ensemble Processing Procedure          .........................          58
                                   4.3.3 Results of QA/QC for N2 through N4           ........................         59
                          4.4      XBT Measurements        ............................................                60
                          4.5      Underway Measurements        ........................................               60
                    5    TECHNICAL DISCUSSION              ............................................                69
                          5.1      Forcing Functions   ..............................................                  69
















                    x

                                                  TABLE OF CONTENTS (continued)

                                                                                                                   PAGE
                                  5. 1.1 Wind      ..................................................                  69
                                  5.1.2 River Discharge        .........................................               70
                                  5.1.3 Eddy-Shelf Interactions      ....................................              73
                          5.2     Integrated Water Column Chemistry         ...............................            76
                                  5.2.1   Temperature      ............................................                76
                                  5.2.2   Salinity   ................................................                  79
                                  5.2.3   Dissolved Oxygen      ........................................               83
                                  5.2.4   Nutrients    ...............................................                 86
                                  5.2.5   Particulate Matter Distributions     .............................           91
                                  5.2.6   Phytoplankton Pigments       ...................................            100
                                  5.2.7   Integration of Water Column Properties       .......................        105
                    6     LITERATURE CITED           ................................................                 107















                                                                                                                            xi


                                                               LIST OF FIGURES



                     FIGURE                                                                                             PAGE
                     1.2.1    Station locations and cross-shelf line numbers for NEGOM hydrographic/
                              ADCP cruises and geographic locations in the study area        . ..................             3
                     3.1.1    Station locations for cruise N3 conducted 25 July - 6 August 1998         . ..........        13
                     3.1.2    Station locations for cruise N4 conducted 13 - 24 November 1998           . ..........        22
                     3, 1 *1  Station locations for cruise N5 conducted 15 - 28 May 1999         . ...............          32
                     3.2.1    Locations of ensemble ADCP data for cruises N3, N4, and N5           ...............          45
                     3.2.2    Locations of discrete samples filtered for calbration at sea of flow-through
                              fluorometer data on cruises N3, N4, and N5       . ............................               48
                     4.1.1    Composite potential temperature-salinity diagram for stations from cruise N3
                              (July/August 1998)    ..................................................                      52
                     4.1.2    Composite potential temperature-salinity diagram for stations from cruise N4
                              (November 1998)     . .................................................                       53
                     4.2.1    Phosphate versus nitrate for 1998 cruises N2 (spring), N3 (summer), and N4 (fall). 54
                     4.2.2    Ensemble upcast CTD salinity versus bottle salinity for 1998 cruises N2
                              (spring), N3 (summer), and N4 (fall)     . ..................................                 55
                     4.2.3    Dissolved oxygen versus upcast sigma-theta for 1998 cruises N2 (spring),
                              N3 (summer), and N4 (fall)    . .........................................                     56
                     4.5.1    Flow-through fluorometer calibration for cruise N3 (July/August 1998)          ........       62
                     4.5.2    Flow-through fluorometer calibration for cruise N4 (November 1998)            .........       63
                     4.5.3    Flow-through fluorometer calibration for cruise N5 (May 1999)           ..............        64
                     4.5.4    Salinity and chlorophyll a at about 3-m depth on cruise N2 (May 1998)          . ......       65
                     4.5.5    Salinity and chlorophyll a at about 3-in depth on cruise N3 (July/August 1998). .             66
                     4.5.6    Salinity and chlorophyll a at about 3-m depth on cruise N4 (November 1998). . .               67
                     5.1.1    Wind vector field at 0700 UTC on (a) 21 November 1998 and
                              (b) 22 November 1998     . .............................................                      71
                     5.1.2    Daily discharge rates for the (a) Mississippi River at Talbert Landing (64-yr
                              record) and (b) Tombigbee River at Demopolis, AL (70-yr record)           . ..........        72
                     5.1.3    Daily sea surface height anomaly (hindcast) from satellite altimeter data for:
                              (a) 19 November 1997, NI cruise; and (b) 13 May 1998, N2 cruise           . ..........        74
                     5.1.4    Daily sea surface height anomaly (hindcast) from satellite altimeter data for:
                              (a) 29 July 1998, N3 cruise; and (b) 18 November 1998, N4 cruise          . ..........        75
                     5.2.1    Potential temperature ('C) at 3.5 m on NEGOM hydrographic cruises             .........       77
                     5.2.2    Potential temperature ('C) on line 6 of cruise N3, 26 July - 6 August 1998. . . . .           80
                     5.2.3    Salinity, from CTD data, at 3.5 m on NEGOM hydrographic cruises             . .........       81
                     5.2.4    Salinity, from CTD data, on line 6 of cruise N3, 26 July - 6 August 1998         . .....      84
                     5.2.5    Dissolved oxygen (mL-L-1) on line 6 of cruise N2, 5-16 May 1998           ............        85
                     5.2.6    Nitrate (ptM) on line 1 of cruise N2, 5-16 May 1998       . .....................             88
                     5.2.7    Phosphate (pM) on line I of cruise N4, 13 -24 November 199 8         ...............          89
                     5.2.8    Phosphate (pM) on line 6 of cruise N4, 13-24 November 1998           ...............          90












                    xii

                                                     LIST OF FIGURES (continued)



                    FIGURE                                                                                         PAGE
                    5.2.9   Silicate (uM)on line 1 of cruise N2, 5-16 May 1998    .......................          92
                    5.2.10  Light transmission (%; 660 nm wavelength; 25-cm path length) on line I
                            of cruise N2, 5-16 May 1998    . ........................................                 94
                    5.2.11  Particulate material (ug.L-1) at 3.5 m on NEGOM hydrographic cruises        ........     96
                    5.2.12  Particulate organic carbon (ug.L-1) at 3.5 m on NEGOM hydrographic cruises         ...   98
                    5.2.13  Chlorophyll a (ng.L-1) at 3.5 m on NEGOM hydrographic cruises          .............      102
 










                                                                                                                        xiii


                                                              LIST OF TABLES



                     TABLE                                                                                          PAGE
                     2.1.1   Cruise identifiers and dates   ............................................                  7
                     2.2.1   Spatial scales (km) of temperature from a depth of 10 in     . ...................           8
                     2.2.2   Spatial scales (km) of ADCP current velocity components at a depth of 14 in. . . .           9
                     3.1.1   Times and locations for CTD stations on cruise N3       ........................           14
                     3.1.2   Number of bottles sampled by variable on cruise N3       .......................           16
                     3.1.3   Launch times and locations for XBT drops on cruise N3        ....................          19
                     3.1.4   Times and positions for CTD stations on cruise N4       ........................           23
                     3.1.5   Number of bottles sampled by variable on cruise N4       .......................           26
                     3.1.6   Launch times and locations for XBT drops on cruise N4        ....................          28
                     3.1.7   Times and positions for CTD stations on cruise N5       ........................           34
                     3.1.8   Number of bottles sampled by variable on cruise N5       .......................           36
                     3.1.9   Launch times and locations for XBT drops on cruise N5        ....................          39
                     3.2.1   Hydrographic equipment available on cruises N3, N4, and N5          ...............        42
                     3.2.2   Bottle tripping locations  ......................................              I .......   43
                     3.2.3   Dates and quantity of ADCP data      ......................................                44
                     3.2.4   ADCP configuration summary       . .......................................                 46
                     3.3.1   Summary of data collection and scientific participation on NEGOM-COH cruises.              49
                     3.3.2   Complementary programs on NEGOM-COH hydrography surveys                 . ..........       50
                     4.3.1   Complex regression statistics for GPS velocity versus bottom-track velocity on
                             cruise N2 through N4    . ..............................................                   57
                     4.3.2   Results of evaluation of ADCP data for external factors on cruises N2
                             through N4 and number of data segments rejected       . .......................            58
                     5.2.1   Summary of water column temperature, salinity, and dissolved oxygen           ........     79
                     5.2.2   Summary of water column dissolved nutrients        ............................            87
                     5.2.3   Summary of water column particulate properties        ..........................           93
                     5.2.4   Summary of water column particulate pigment concentrations           ...............       101















                                                                        xv


                              ACRONYMS AND ABBREVIATIONS



            ADCP        acoustic Doppler current profiler
            AVIM        Advanced Very fligh Resolution Radiometer satellite
            CCAR        Colorado Center for Astrodynamics Research
            CTD         conductivity-temperature-depth
            DGPS        differential Global Positioning System
            GPS         Global Positioning System
            JPLC        high performance liquid chromatography
            LATEX       Louisiana-Texas Shelf Physical Oceanography Program
            NEGOM       Northeastern Gulf of Mexico Physical Oceanography Program
            NEGOM-COH   Northeastern Gulf of Mexico Chemical Oceanography and Hydrography
            MMRP        Marine Mammal Research Program at TAMU-Galveston
            MMS         Minerals Management Service, U.S, Department of the Interior
            NOAA        National Oceanic and Atmospheric Administration
            PAR         photosynthetically available radiation
            PI          principal investigator
            PM          particulate matter
            POC         particulate organic carbon
            PON         particulate organic nitrogen
            QAJQC       quality assurance/quality control
            RDI         RD Instruments, Inc.
            RIV         research vessel
            SAIL        Serial ASCII Interface Loop system
            SSC         sea surface chlorophyll fluorescence
            SSHA        sea surface height anomaly
            SSS         sea surface salinity
            SST         sea surface temperature
            TAMU        Texas A&M University
            USF         University of South Florida
            UTC         Universal Coordinated Time
            XBT         expendable bathythermograph probe













                                                    1 EXECUTIVE SUMMARY



                              Introduction


                   The Minerals Management Service (MMS) of the U. S. Department of the Interior supports the
                   Northeastern Gulf of Mexico Physical Oceanography Program (NEGOM). NEGOM is divided
                   into six study units, one of which is the Chemical Oceanography and Hydrography Study
                   (NEGOM-COH). NEGOM-COH covers the east Louisiana-Nfississippi-Alabama-west Florida
                   continental shelf and upper slope from the Mississippi River delta to Tampa Bay in water depths
                   of 10 to 1000 in. This report focuses on the second year of work of NEGOM-COH covering the
                   period July 1998 through June 1999. It does not contain detailed syntheses or interpretation of
                   data collected; those will be detailed in the Final Synthesis Report.

                   The contract for NEGOM-COH was awarded to the Texas A&M Research Foundation on 30
                   September 1997. Through the contract, components of the Texas A&M University System, a
                   combination of Texas institutions of higher learning and Texas state agencies dedicated to
                   training, research, and extension, conduct the NEGOM-COH study. In addition to support from
                   the NIMS, financial backing for NEGOM-COH is provided by Texas A&M University (TAMU),
                   a component of the System. TAMU is assisted in this program by a subcontract with Dr. Robert
                   R. Leben of the University of Colorado.

                   The major objective of NEGOM-COH is to describe spatial and temporal distributions and
                   variations of hydrographic variables, and the processes that contribute to them. It will be met
                   through completion of a three year field program of hydrographic/acoustic Doppler current
                   profiler (ADCP) cruises in the spring, summer, and fall seasons, after which observations will
                   be synthesized, interpreted, and reported to provide a more complete understanding of
                   circulation and distribution of properties over the study area.

                   Program management is provided by Dr. Worth D. Nowlin, Jr., Program Manager, and Dr. Ann
                   E. Jochens, Deputy Program Manager. Study tasks are:

                     Task 1, Field Work and Data Collection
                              Dr. Douglas C. Biggs, Co-principal investigator (Co-PI)
                              Dr. Norman L, Guinasso, Jr., Co-PI
                              Dr. M. C. Kennicutt IL Co-PI
                   - Task 2, Data Reduction/Analysis and Synthesis
                              Dr. Ann E. Jochens, Principal Investigator (PI)
                              Dr. Matthew K. Howard, Co-PI
                   - Task 3, Information/Data Synthesis and Technical Reports
                              Dr. Worth D. Nowlin, Jr., PI
                              Professor Robert 0. Reid, Co-PI
                              Dr. M. C. Kennicutt 11, Co-PI











                   2


                   1.2         Field Data


                   Three hydrographic/ADCP survey cruises were conducted in the report period: Cruise N3 during
                   25 July - 6 August 1998; cruise N4 during 13-24 November 1998; and cruise N5 during 14-28
                   May 1999. Conductivity-temperature-depth (CTD) and bottle sampling were completed at 98,
                   99, and 102 stations and expendable bathytherniographs (XBT) were launched successfully at
                   10 1, 112, and 96 stations. ADCP data were recorded continuously along track on N3 and N5;
                   but due to equipment malfunction, data were collected only along lines I through 4 on cruise
                   N4. The standard pattern of station locations and line numbers, as well as bathymetry and
                   geographic locations, are shown in Figure 1.2. 1. At each CTD/bottle station, continuous profiles
                   were made of conductivity, temperature, dissolved oxygen, downwelling irradiance,
                   backscatterance, fluorescence, and percent transmission. Up to 12 water samples were taken
                   at each station and analyzed for dissolved oxygen and six nutrients: nitrate, nitrite, phosphate,
                   silicate, urea, and ammonium. Typically at 60 stations, water samples were analyzed for
                   phytoplankton pigments, particulate matter, and particulate organic carbon/particulate organic
                   nitrogen. Bottle salinities were measured at the innermost and seawardmost stations of each
                   cross-shelf line, as well as at supplemental stations for problem solving associated with bottle
                   sampling. XBT stations were taken between cross-shelf CTD stations to increase the resolution
                   of the temperature data to -10 km. Near-surface temperature, salinity, and fluorescence were
                   logged every two minutes while the ship was underway or stopped at stations. To calibrate the
                   underway fluorescence, 101, 108, and 102 underway water samples were analyzed for
                   chlorophyll content. After collection, the data sets were processed for compliance with quality
                   assurance and quality control criteria.

                   1.3         Technical Discussion


                   This second annual report focuses on the data collection and processing activities of
                   NEGOM-COH from July 1998 through June 1999. Section 5 provides a brief description and
                   examples of representative forcing functions-wind, river discharge, and offshelf eddies-and
                   of the water column properties for the first four NEGOM cruises: N I (November 1997), N2
                   (May 1998), N3 (July/August 1998), and N4 (November 1998). No detailed syntheses of data
                   are given, but the results of several preliminary analyses associated with interesting phenomena
                   are presented to show examples of representative products to be provided in the final report.

                   1.3.1      Forcing Functions

                   Ancillary data sets are being acquired to allow examination of various forcing functions that
                   influence water properties and circulation in the NEGOM study area. These include
                   meteorological data from marine buoys and coastal land stations, river discharge rates, and sea
                   surface height anomaly fields from satellite altimeters.

                   Production of gridded wind fields allowed examination of the time series of daily winds over
                   the study area. Throughout most of the NI cruise, winds were directed to the south and




                          Ift" V*









                        31*N

                                                 bi_            - - ----

                                                                                    F            P"



                                                                       0
                        30*N                         0
                                                               0              0
                                                                      0      0
                                                                    0
                                                      0
                                                                    0      0

                                                       0       0
                                                                  0      0
                                                                                                                             M,
                                                                                          0
                                                                                                         0
                                                                                                                              727-,@, Ik".
                                                             4   0                     0
                                                                                                                              gw F",-'
                                                         3   p,
                        29*N                                0  5      0                            0
                                                                   0
                                                   2                                 0
                                                                         0
                                                                 0                            0
                                                                                   0
                                                      CIO      6                           0
                                                                      0
                                                                                        0
                                                                            0         0
                                                                   7                                       0
                                                                           0      0
                                                                                  0
                                                                                0
                                                                                            %_0
                        28*N
                                                                               9

                                                                                                                                F, A
                                         * CTDIBottle Stations
                                         * XBT Stations
                                                                                      11 @O 0 0.)0 0    0 0 0      0
                                                                                                                        0

                        27*N                                                                             k I
                          901W         89'W         88*W          87*W         86'W        85'W         84'W         83*W         82*W




                     Figure 1.2. 1. Station locations and cross-shelf line numbers for NEGOM hydrographic/ADCP cruises and geographic
                                   locations in the study area. Line numbers are given at the offshore end of the lines.











                   4

                   southwest, in response to the presence of high pressure over the continent to the north. On N2,
                   there were several periods with upwelling-favorable, but weak, westerly winds, particularly
                   near-shore.

                   Winds during the N3 cruise were generally weak and varied from westerly to easterly. Winds
                   were variable in direction and speed throughout cruise N4. Frontal passages moved through the
                   study area during N I, N2, and N4, but no major cold fronts passed through the region during the
                   N3 cruise (summer 1998).

                   During winter 1998, discharge from rivers in the study region generally exceeded the long-term
                   mean, many by significant amounts. In spring 1998, the Mississippi River continued to
                   discharge at a rate well above its mean. Other rivers had flows below their means, except in late
                   April 1998, when rivers west of the Apalachicola exhibited a brief pulse of much greater than
                   average discharge. Rivers examined east of Cape San Blas generally had only one episode (in
                   March) of high discharge during the first half of 1998. Greater than average river discharge into
                   the Gulf from Mississippi Sound to Cape San Blas during early 1998 is consistent with an
                   extensive surface expression of fresh water observed during cruise N2 in May 1998.

                   Cyclonic and anticyclonic eddies in deep water near the shelf have been observed to have
                   profound influence on the outer shelf circulation in the northeastern Gulf. During the four
                   cruises, an anticyclonic eddy was located to the west of and extending into the DeSoto Canyon.
                   The shape of these eddies varied from cruise to cruise, but they influenced an anticyclonic
                   offshore circulation at the shelf edge in the western part of the study area. The eastern shelf was
                   under the influence of cyclonic flow. These eddies variously moved shelf water offshore and
                   deep water onshore.

                   1.3.2       Integation of Water Column Chemigta

                   The water column chemistry component is designed to provide an integrated understanding of
                   the chemistry of dissolved oxygen, nutrients, and particulate constituents in the study area.
                   Dissolved and particulate fractions within the water column are closely coupled through the
                   processes of photosynthesis, excretion, decomposition, and diagenesis. Particulate water
                   colu min constituents (particulate matter (PM), particulate organic carbon (POC), and
                   phytoplankton pigments) are characterized as living and non-living, organic and inorganic, and
                   phytoplankton-derived. Temperature, salinity, dissolved oxygen, nutrient, PM, POC, and
                   phytoplankton pigment distributions were examined for cruises NI through N4. Preliminary
                   results are presented in Section 5.2 and several are summarized below.

                   Nutrient distributions during the cruises exhibited classical marine patterns with near surface
                   waters (down to 100 in) depleted in nutrients due to biological uptake, deep waters enhanced
                   in nutrients due to remineralization, and enhanced concentrations near river outflows due to the
                   inflow of nutrient rich waters. In shallow depths the entire water column was often depleted in
                   nutrients since the euphotic zone reached to the bottom of the water column. The major












                                                                                                                       5

                    phytoplankton nutrients (nitrate, phosphate, and silicate) showed variations with location, water
                    depth, and time of year.

                    During most cruises at most locations, dissolved oxygen concentrations in near-surface waters
                    were near or above the atmospheric equilibrium. On occasion, elevated near-surface water
                    dissolved oxygen concentrations were observed due to the local production of oxygen by
                    photosynthesis. Near-bottom water dissolved oxygen concentrations decreased with increasing
                    distance from shore and increasing bottom water depth. In the spring and summer, near-shore
                    bottom oxygen levels became depleted over those observed during the fall sampling periods.
                    Seasonal variations at shallow water sites coincided with increased exposure of the sea bottom
                    to sunlight.

                    In general, waters in the study area had high light transmission during all seasons, indicating few
                    particles were present. Light transmission was lowest and PM concentrations greatest close to
                    the Mississippi River, reflecting riverine inputs of particulate matter.           Some reduced
                    transmission was indicated at the shallowest stations over the eastern study area, indicating
                    outflow of particulate-laden water from the Apalachicola and Suwannee Rivers. In general,
                    POC in near-surface waters accounted for 25 to 40% of the PM, while in near-bottom water
                    POC was about 7 to 20% of the PM.


                    Near-surface water chlorophyll a concentrations generally were similar to the maximum
                    concentrations in vertical profiles. In contrast to PM and POC distributions, chlorophyll a was
                    relatively uniformly distributed across the shelf regions of the study area. Elevated chlorophyll
                    a values were associated with discharges from the smaller rivers that carried moderate PM loads
                    and nutrient-rich waters. Regionally, near-sur&6e chlorophyll a concentrations differed during
                    each sampling period with highs in the southeast region in November 1997, along the
                    Mississippi Bight in May 1998, off the Nfississippi River in July/August 1998, and a uniform
                    distribution in November 1998.          The predominant accessory pigments detected were
                    19-butanoyloxyfucoxanthin, facoxanthin, 19-hexanoyloxyfucoxanthin, chlorophyll b, c, c,
                    zeaxanthin, and 0-carotene. Other accessory pigments that were present in trace amounts
                    included: violaxanthin, peridinin, prasinoxanthin, diadioxanthin, diatoxanthin and alloxanthin.

                    Water column properties were cross-correlated. Potential temperature was positively correlated
                    with time of year, distance from shore, depth in the water column, and total depth of the water
                    column. Salinity was negatively correlated with nutrient and particulate matter concentrations
                    and positively correlated with light transmission. Dissolved nutrients were positively correlated
                    with each other and with PM and POC. However, nutrient concentrations were only moderately
                    correlated with phytoplankton pigment concentrations suggesting that a significant non-living
                    particulate matter source affected particulate distributions in the study area (i.e., an overriding
                    influence ofriver discharges). Phytoplankton pigment concentrations were negatively correlated
                    with salinity, with some being more highly correlated than others (0-carotene, diadioxanthin,
                    and alloxanthin). Chlorophyll a was positively correlated with other phytoplankton pigments.











                                                                                                                         7
                                                           2 INTRODUCTION



                    The first annual report for NEGOM-COH detailed the program objectives, tasks, and
                    participants, the data collection and processing for cruises Nl and N2, and the results of
                    preliminary examination of the NI data set (Jochens and Nowlin, 1998). The second annual
                    report focuses on the period from July 1998 through June 1999 and includes data acquisition on
                    cruises N3, N4, and N5, and QA/QC and analysis for selected data from cruises N2, N3, and N4.
                    Information on the NEGOM-COH program is provided on a publicly accessible web page on
                    the internet at http://negom.tamu.edu/negom.



                    2.1         Overview of Cruise Schedule and Nomenclature


                    Three hydrographic/ADCP cruises were conducted aboard RIV Gyre during this report period.
                    The cruises, their various designators, and their start and end dates are given in Table 2. 1. 1. The
                    NEGOM ID is the shorthand identifier used, in this report. The cruise ID number is the standard
                    cruise identifier widely used in the oceanographic community. The first two characters are the
                    year of the cruise, the third character is the ship identifier, G for Gyre, and the last two
                    characters are the number of the ship's cruise for that year. Typical station locations and
                    cross-shelf line numbers are shown in Figure 1.2. 1.




                                                Table 2. 1. 1. Cruise identifiers and dates.


                          Survey          Start Date               End Date          NEGOM 11D Cruise ID
                            No.

                             3           25 July 1998            6 August 1998             N3           98-G-10

                             4        13 November 1998 24 November 1998                    N4           98-G-15

                             5           15 May 1999             28 May 1999               N5           99-G-07




                    2.2         Programmatic Changes


                    Near-surface temperature and velocity spatial scales for NEGOM cruises N I through N4 were
                    estimated. Temperature scales were based on temperatures recorded at about I 0-m depth from
                    both XBT drops and CTD casts. Scales were estimated by interpolating the I 0-m temperature
                    data along each cruise track to regularly spaced intervals and removing a quadratic fit to take
                    out the large spatial scale background field. A fast Fourier transform was used to estimate the
                    auto-correlation function of the residual series. The spatial scale was defined as the first











                    8
                    zero-crossing ofthe auto-correlation ftmction. Spatial scales for the four cruises are summarized
                    in Table 2.2. 1; scale values marked with an asterisk are considered less reliable because the ratio
                    of the variance of the residual temperature series (raw minus quadratic fit) to the variance of the
                    raw temperature series is less than 0. 10.



                                Table 2.2. 1. Spatial scales (km) of temperature from a depth of 10 m.


                                 Line No.            N1              N2              N3              N4
                                     1             5.26*            5.59           6.14*            6.34
                                     2             7.47           13.68           10.90             9.13
                                     3             8.84*          10.76           10.83           10. 17*
                                     4            15.67*          12.76           10.29           12.55
                                     5            10.46*          15.89             8.84          22.06
                                     6             23.91          17.42           20.33           27.38
                                     7            18.54*          26.16           15.73           23.89
                                     8            20.13           22.44             9.55          25.65*
                                     9            18.85           23.55*          30.34           25.77
                                     10           28.51           16.75           20.90           15.74*
                                     11           26.14           20.01*          14.06           21.92
                                  1000M           17.50*          16.44           18.60           27.43
                                 less reliable; small ratio of variances of residual to raw temperatures




                    In general, cross-shelf scales are smaller in the western region of the NEGOM study area than
                    in the east on the West Florida Shelf Values range from 5-6 km close to the Mississippi River
                    Delta (line 1), where there is steep bathymetry, and increase to 10- 15 km on the western edge
                    of DeSoto Canyon (lines 2-5), where the continental shelf broadens slightly before dropping off
                    rapidly into the canyon. On the eastern edge of DeSoto Canyon and on the West Florida Shelf
                    (lines 6-11), the bathymetry is less steep and the fall-off of the continental shelf and slope is
                    gradual. There, spatial scales range from 20-30 km.

                    Along the 1000-m isobath, alongshelf scales range from 16-27 km. On N4, scales estimated
                    from NBT/CTD data (-10-m depth and -10 kin apart) were similar to those from the ship's
                    flow-through thermosalinograph (-3-m depth and logging data every 2 minutes).

                    Spatial scales at 14 m depth based on current speeds from ADCP measurements were estimated
                    using the same procedures as used for temperature scales. The number of independent samples
                    per line for velocity were roughly every 1. 5 km, which is considerably denser than the 10 km
                    for temperature. Table 2.2.2 summarizes the along- and cross-track velocity component scales











                                                                                                                    9
                    for each of the four cruises. Again, a quadratic fit was removed prior to estimating the
                    auto-correlation function. On cruise N4, ADCP data were taken only on lines 1-4 due to
                    instrument malfunction.




                          Table 2.2.2. Spatial scales (km) of ADCP current velocity components at a depth
                                          of 14 m. Along-track scales are given first, then cross-track scales.

                                Line             N1               N2               N3               N4
                              Number       Along Cross Along Cross Along Cross Along Cross
                                  1           5       5        6       3        4       5        2       5
                                  2           7       4        12      11       14      14       9       11
                                  3           10      7        10      10       7       13       5       3
                                  4           6       6        14      13       3       4        9       9
                                  5           25      6        7       18       12      13
                                  6           20      11       19      29       22      20
                                  7           27      12       25      15       14      25
                                  8           32      25       20      21       16      24
                                  9           29      14       34      21       36      26
                                  10          21      19       27      32       32      25
                                  11          23      20       17      19       12      23
                               1000m          50      51       31      30       35      18
                                  no data available for analysis


                    As with temperature scales, scales of velocity components generally are smaller in the western
                    region than on the broad shelves of the eastern region. Scales increase from 2-6 km near the
                    Mississippi River Delta (line 1) to nominally 4-18 kin on lines 2-5. The scales increase on the
                    West Florida Shelf to a range of 20-35 km. The longest spatial scales are found along the
                    I 000-m isobath; these probably are due to the influence of eddies. There is no clear relation of
                    along-track versus cross-track scales, although there seems a tendency for along-track scales to
                    be slightly greater than cross-track. One might expect cross-shelf scales to be smaller than
                    along-shelf scales (Nowlin et al., 1998a).

                    Based on these results, one, rather than two, XBTs were deployed between CTD station
                    locations along the 1 000-m isobath beginning with cruise N5.

                    2.3         Report Organization

                    This is the second annual report of the NEGOM-COH study, reporting on: data-gathering
                    efforts; equipment, measurement and analytical methodologies employed; results of quality
                    control exercises and determinations; status of data archiving and data sharing with other
                    contractors; and preliminary data analysis and results of data collected to date. More extensive











                  10
                  analyses or,syntheses of the information will be provided in the final Synthesis Report at the
                  conclusion of the study. Section 3 of the report details the acquisition of the chemical
                  oceanography, hydrography, and ADCP measurements and collateral data assembly. Section
                  4 discusses data processing efforts and data quality control methods and results. Section 5
                  provides technical discussion of the data, with samples of data products for the various data
                  types. All times are reported in Universal Coordinated Time (UTC) unless stated otherwise.












                                                        3 DATA ACQUISITION



                    An overview of the NEGOM-COH data acquisition activities for cruises N3, N4, and N5 is
                    presented in this section. It covers in situ sampling efforts and the instrumentation, calibration,
                    and sampling procedures, and summarizes field data collection and collateral data assembly.

                    3.1         General Description of Surveys

                    From July 1998 through June 1999, three hydrographic/acoustic Doppler current profiler
                    (ADCP) surveys (N3, N4, and N5) were conducted aboard the RIV Gyre. A Sea-Bird
                    SBE-91 lplus was used on each cruise. Conductivity-Temperature-Depth (CTD)-Rosette stations
                    were occupied on each cruise at nearly identical station locations. A test station, at which all
                    bottles were tripped in the salinity minimum water at about 700-800 in, was made on each cruise
                    to test the instrumentation and equipment. Expendable bathythermograph (XBT) probes were
                    launched between CTD stations. ADCP data were collected along the cruise tracks. Navigation
                    data and station locations were determined by differential Global Positioning System (DGPS).

                    The surveys consisted of I I lines of CTD and XBT stations perpendicular to the bathymetry
                    (cross-shelf lines). Lines are numbered from I to 11, west to east. The naming convention for
                    cross-shelf lines is:


                            First and second characters:                NEGOM cruise number (N3, N4, or N5)
                            Third character:                            L = Line
                            Fourth and fifth characters:                Line number (1 through 11)
                            Sixth character:                            S = Sequence
                            Seventh and eighth characters:              Sequence number of station on the line
                            Ninth character:                            C = CTD station type; X = XBT station type

                    Stations on each cross-shelf line are numbered sequentially from innermost to outermost station
                    regardless of station type. As an example, station N3LO6SO3C is the third station from the coast
                    on line 6 and is a CTD station taken on cruise N3. Where it is clear which station type is being
                    described, the ninth character is not included in the tables below.

                    XBTs were deployed between pairs of cross-shelf lines along the 1000-m isobath. The station
                    naming convention for these stations is:

                            First and second characters:                NEGOM cruise number (N3, N4, or N5)
                            Third character:                            X = Segment between two cross-shelf lines
                            Fourth and fifth characters:                Starting cross-shelf line number of segment
                            Sixth and seventh characters:               Ending cross-shelf line number of segment
                            Eighth character:                           Sequence number of station between lines
                            Ninth character:                            X = XBT station type











                   12

                   For example, station N4X09 1 OMX is the second XBT deployed on cruise N4 between lines 9
                   and 10 (M = midway).

                   3.1.1       Cruise N3


                   The third NEGOM-COH hydrography cruise (N3) was conducted on the RIVGyre from 25 July
                   - 6 August 1998. It was staged out of Gulfport, MS, and returned to Galveston, TX. Dr.
                   Douglas C. Biggs and Dr. Norman L. Guinasso, Jr., were co-chief scientists. One hundred CTD
                   stations, including one test station located in deep water in DeSoto Canyon (Station 000,
                   N3TEST04) and one supplementary station in Mississippi Canyon (Station 099, N3MOO001),
                   were completed and 108 XBT drops were made. The locations of the CTDs and XBTs and
                   cruise track are shown in Figure 3. 1. 1. The test station was taken approximately at the location
                   of the seawardmost CTD station on line 4. The cruise track starts at this location and runs along
                   the I 000-m isobath to the seawardmost station on line I I where the CTD/XBT station series
                   began. XBTs were dropped and ADCP data were collected along this 1000-m track. Only
                   locations of the 10 1 successful XBT drops are shown in Figure 3. 1. 1. Station number, date,
                   time, location, water depth, and number of bottles tripped at each CTD station are given in
                   Table 3. 1. 1. '                                                                                             #
                   Stations at which bottle samples were taken are summarized in Table 3.1.2. Nutrients and
                   oxygen were measured from every Niskin bottle sampled. Salinity was measured at the
                   inner-most station and the 1000-m isobath station on each cross-shelf line, the test station, and
                   the supplemental station for a total of 24 stations. Pigment samples were taken at the top, at the
                   chlorophyll-maximum (as estimated from the downcast fluorescence trace), and in the low light
                   regime immediately below the chlorophyll-maximum at 58 stations. Total particulate matter
                   (PM), particulate organic carbon (POC), and particulate organic nitrogen (PON) were measured
                   from the shallowest and deepest bottles and, for PM, from a middle, "clear water" bottle at 60
                   stations.


                   The location, date, time, total water depth, and probe type of the 10 1 XBT drops that produced
                   usable data are given in Table 3.1.3. The l50kHz broad-band ADCP was operated 6ontinuously
                   along the survey track (Section 3.2.3). Flow-through near-surface temperature, conductivity, and
                   fluorescence were logged every 2 minutes (Section 3.2.5). Surface samples were filtered and
                   analyzed for chlorophyll a content to calibrate the flow-through fluorometer at 10 1 locations.

                   Seven complementary research efforts were accommodated on summertime cruise N3. Thirty
                   ARGOS-tracked drifters were launched for Dr. James M. Price of MMS. A marine mammal
                   survey with bigeye binoculars was carried out by Dr. Sasha Drobyshevski from the
                   TAMU-Galveston Marine Mammals Research Program (MIARP) to continue and extend similar
                   surveys done on N I and N2. M1V1RP survey objectives are to obtain data on the distribution and
                   abundance of marine mammals and to compare sightings with locations of surface temperature,
                   salinity, and fluorescence fronts. Ms. Nancy Hess, a graduate student of Dr. Christine Ribic at
                   the University of Wisconsin, was assisted by Mr. Mike Seymour, an undergraduate student at


















                       31*N

                                                                                                                                W"






                                                                                                                                 N
                                                                                                                             R",
                       30*N
                                         A






                                                            4
                                                                                                                               @W'
                       29*N                             3
                                                 2


                                                              6


                                                                 7

                       28'N -                                          8
                                                                             9
                                        e CTDIBottle - 98 Stations
                                        o XBT - 101 Stations                     10
                                          Mississippi Canyon Mooring Station                   T
                                                                                        0
                                                                                                     00

                       27-N
                          90*W        89*W         88*W         87'W         86'W        85*W         84*W         83*W         82*W





                     Figure 3. 1. 1. Station locations for cruise N3 conducted 25 July - 6 August 1998. CTD stations began with the most
                                  seaward station on line 11. The thick line shows the cruise track, which began at the location of the most
                                  seaward station on line 4.











                       14

                       Louisiana State University, and Mr. Michael Goldstein, a graduate student in Wildlife and
                       Fisheries Science Department at TAMU, to carry out a companion census of seabird
                       distributions and abundances. This continued and extended Ms. Hess' participation in
                       summertime seabird surveys of the northeast Gulf during RIV Gyre cruises 96-G-06 and
                       97-G-07. Fifteen plankton tows were made by Ms. Rebecca Scott, TAMU graduate student of
                       Dr. Biggs, for her M.S. thesis research. Mr. Josh Rigler, graduate student of Dr. George Born
                       and Dr. Robert Leben, Colorado Center for Astrodynamics Research (CCAR), University of
                       Colorado, participated in the cruise as part of a training exercise to provide hands on experience
                       in collection of in situ oceanographic data used to compute upper layer density, dynamic height,
                       and geostrophic volume transport for comparison with TOPEX/Poseidon and ERS-2 radar
                       altimetry. Dr. Chuanmin Hu and Mr. Denis Nadeau, from the remote sensing group headed by
                       Dr. Frank Muller-Karger at the University of South Florida (USF), conducted irradiance casts
                       and collected dissolved organic carbon data for comparison with SeaWiFS data. Ms. Cheryl
                       Burden, M.S. student in oceanography at TAMU whose MS thesis project is to determine and
                       quantify the dominant modes of offshelf sediment transport in the Mississippi Canyon, retrieved
                       and then redeployed a current meter mooring in Mississippi Canyon which had been collecting
                       data since May 1998. Further information on these complementary research programs can be
                       obtained from the scientists involved.





                                         Table 3. 1. 1. Times and locations for C7D stations on cruise N3.


                           Station        Station            Date           Time       Latitude      Longitude       Depth      No. of
                          Number          Name              (UTC)          (UTC)          (ON)          (OW)           (m)      Bottles
                             000         N3TEST04       26-PJL-1998        16:41:54    29.194575     -87.348250        980.        12
                             001         N3LllSl8       27-RTL-1998        12:44:04    27.500080     -85.395098        992.        12
                             002         N3LIlSl6       27-JUL-1998        14:56:55    27.500658     -85.225935        748.        12
                             003         NMIIS14        27-JUL-1998        16:56:41    27.500395     -85.075703        488.        12
                             004         N31,11S12      27-JUL-1998        20:14:22    27.498985     -84.886485        288.        12
                             005         N31,11SIO      27-JUL-1998        22:07:48    27.500232     -84.681948        198.        12
                             006         N3LllSO8       28-JUL-1998        00:59:23    27.499115     -84.343575        100.        12
                             007         N3LllSO6       28-JUL-1998        03:58:54    27.499222     -83.943143        51.         5
                             008         N3LllSO4       28-JUL-1998        07:03:27    27.499472     -83.496608        35.         5
                             009         NMIIS02        28-RJL-1998        10:28:18    27.500342     -83.009483        12.         5
                             010         N3LllSOl       28-FJL-1998        11:43:02    27.496920     -82.853317        10.         4
                             Oil         N3LIOS01       28-JUL-1998        20:08:21    28.607138     -83.052715        9.          4
                             012         N3LIOS03       28-JUL-1998        22:17:22    28.520875     -83.331748        20.         4
                             013         N3LIOS05       29JUL-1998         00:49:31    28.400247     -83.701397        30.         4
                             014         N3LIOS07       29-JLTL-1998       03:14:17    28.286145     -84.058880        35.         4
                             015         N3LIOS09       29-JUL-1998        05:42:40    28.175358     -84.403378        56,         5
                             016         N3LIOS11       29-RJL-1998        07:45:57    28.083790     -84.681435        85.         11
                             017         N3LIOS13       29-JUL-1998        09:27:10    28.023458     -84.878208        197.        12
                             018         N3LlOSl5       29-RJL-1998        11:12:19    27.961125     -85.073535        310.        12
                                         N3LIOS17                                                                      490.
                             019                        29-JUL- 1998       13:05:02    27.895987     -85.277038                    12
                             020         N3LlOSl9       29JUL-1998         14:41:11    27.852705     -85.411623        651.        11











                                                                                                                                        15


                                 Table 3. 1. 1. Times and locations for CTD stations on cruise N3 (continued).

                           Station        Station            Date           Time       Latitude      Longitude      Depth      No. of
                           Number          Name             (UTC)         -(UTQ          (ON)           (OW)           W       Bottles
                              021       NMOS21          29-JU-1998        17:24:36     27.782648     -85.630720        994.       12
                              022       MUM]            29-JLTL-1998      22:48:39     28.016968     -86.042252        985.       11
                              023       N3LO9SI9        30-JUL-1998       01:07-:28    28-116248     -85.877852        669.       12
                              024       N3LO9SI7        30-JUL-1998       03:30:22     28.190623     -85.754563        494@       12
                              025       N3LO9SI5        30-RTL-1998       05:46:43     28309618      -85.562852        304.       12
                              026       N3LO9SI3        30-Jn-1998        07:33:46     28.411222     -85.395960        198.       12
                              027       N3LO9SII        30-JUL-1998       09:13:20     28.508450     -85.235897        161.       12
                              028       N3LO9SO9        30JUL-1998        11:0439      28.625452     -85.044378        98.        12
                              029       N3LO9SO7        30-Jn-1998        13:49:16     28.838727     -84.693840        46.        4
                              030       N3LO9SO5        30-JLTL-1998      17:07:03     29.104373     -84.255880        27.        4
                              031       N3LO9SO3        30-JUL-1998       20:19:08     29.341822     -83.860818        19.        4
                              032       N3LO9SOI        30-fUL-1998       22:50:28     29.531430     -83.570333        8.         4
                              033       N3LO8SOI        31-JUL-1998       06:12:29     29.621713     -84.785898        8.         4
                              034       N3LO8SO3        31-JUL-1998       08:36:50     29.403607     -84.995545        21.        4
                              035       N3LO8SO5        31-JUL-1998       11:16:16     29.205245     -85.272588        37.        4
                              036       N3L08SO7        31-Jn-1998        14:11:29     28.975060     -85.535807        140.       12
                              037       N3LO8SO9        31--TUL-1998      16:14:36     28.824595     -85.717203        197.       11
                              038       N3LO8SII        31-JUL-1998       19:17:29     28.604903     -85.976282        307.       12
                              039       N3LO8SI3        31-JUL-1998       22:14:27     28.400148     -86.216572        501.       12
                              040       N3LO8SI5        31-JUL-1998       23:54:13     28.292012     -86.340175        693,       12
                              041       N3LO8SI7        01-AUG-1998       02:09:26     28.137015     -86.525497        992,       12
                              042       N3LO7SI7        01-AUG-1998       06:52:52     28.375943     -86.981068        990.       12
                              043       N3LO7S15        01-AUG-1998       09:40:12     28.559653     -86.772890        667.       12
                              044       N3LO7SI3        01-AUG-1998       11:44:04     28.701435     -86.612580        499.       12
                              045       N3LO7SII        01-AUG-1998       13:55:59     28.863668     -86.421413        381.       12
                              046       N3LO7SO9        01-AUG-1998       15:51:39     29.016475     -86.243885        316.       11
                              047       N3LO7SO7        01-AUG-1998       18:19:53     29.207175     -86.027013        200.       12
                              048       N3LO7SO5        01-AUG-1998       20:05:19     29.295125     -85.924100        108.       12
                              049       N3LO7SO3        01-AUG-1998       22:29:28     29.499958     -85.694067        32.        4
                              050       N3LO7SOI        02-AUG-1998       00:34:14     29.686640     -85.479528        21.        6
                              051       N3LO7SOO        02-AUG-1998       01:29:37     29.748238     -85.411762        9.         4
                              052       N3LO6SOI        02-AUG-1998       05:35:17     30.180618     -85.886553        21.        4
                              053       N3LO6SO3        02-AUG-1998       07:10:57     30.019123     -86.026305        33.        5
                              054       N3L06SO5        02-AUG-1998       08:56:45     29.852567     -86.170755        48.        7
                              055       N3L06SO7        02-AUG-1998       10:44:56     29.688697     -86.311607        100.       12
                              056       N3LO6SO9        02-AUG-1998       13:26:53     29.501940     -86.473453        202.       12
                              057       N3LO6SII        02-AUG-1998       15:48:02     29.315217     -86.631220        383.       12
                              058       N3LO6SI3        02-AUG-1998       18:26:24     29.132113     -86.786168        496.       12
                              059       N3L06SI5        02-AUG-1998       21:02:09     28.982292     -86.914093        608.       11
                              060       N3LO6SI7        02-AUG-1998       23:11:44     28.826853     -87.050170        764.       12
                              061       N3LO6SI9        03-AUG-1998       01:39:49     28.653187     -87.202818        996.       12
                              062       N3LO5SI7        03-AUG-1998       07:15:10     29.059607     -87.206327        994.       12
                              063       N3LO5SI5        03-AUG-1998       09:56:50     29.275210     -87.103760        705.       12
                              064       N3LO5SI3        03-AUG-1998       12:10:10     29.467830     -87.010633        486.       12
                              065       N3LO5SII        03-AUG-1998       14:03:32     29.608305     -86.943720        263.       12
                              066       N3LO5SO9        03-AUG-1998       15:22:42     29.725402     -86.886035        199.       12











                                  Table 3. 1. 1. Times and locations for CTD stations on cruise N3 (continued).

                            Station         Station           Date            Time        Latitude      Longitude         Depth    No. of
                           Number           Name             (UTC)            (UTC)         (ON)           (OW)           W        Bottles
                              068        N3LO5SO5        03-AUG-1998        18:59:03      30.028228     -86.737713        101.        7
                              069        N3LO5SO3        03-AUG-1998        21:13:09      30.204203     -86.654452        29.         5
                              070        N3LO5SOI        03-AUG-1998        22:41:35      30.353147     -86.580325        23.         4
                              071        N3LO4SOO        04-AUG-1998        03:10:41      30.299147     -87.345772        9.          4
                              072        N31,04SOI       04-AUG-1998        03:53:50      30.220657     -87.352663        22.         4
                              073        N3LO4SO3        04-AUG-1998        05:45:10      29.979935     -87.352592        29.         5
                              074        N3LO4SO5        04-AUG-1998        07:45:05      29.729598     -87.352253        77.         6
                              075        N3LO4SO7        04-AUG-1998        09:11:48      29.569920     -87.354860        106.        10
                              076        N3LO4SO8        04-AUG-1998        10:18:32      29.532568     -87.351640        193.        12
                              077        N3LO4SIO        04-AUG-1998        11:54:46      29.376225     -87.332367        507.        12
                              078        N3LO4SI2        04-AUG-1998        14:30:36      29.195090     -87.348343        985.        12
                              079        N3L03SIO        04-AUG-1998        20:46:09      29.151810     -87.862398        1024.       12
                              080        N3LO3SO9        04-AUG-1998        22:47:27      29.201073     -87.888850        555.        12
                              081        N3LO3SO8        05-AUG-1998        00:16:45      29.282653     -87.891170        200.        12
                              082        N3LO3SO7        05-AUG-1998        01:08:02      29.339482     -87.886112        101.        8
                              083        N3LO3SO5        05-AUG-1998        03:10:33      29.558542     -87.948972        44.         5
                              084        N3LO3SO3        05-AUG-1998        04:59:21      29.804210     -87.998702        37.         4
                              085        N3LO3SOI        05-AUG-1998        06:52:25      30.019387     -88.042483        23.         4
                              086        N3LO3SOO        05-AUG-1998        07:56:34      30.143178     -88.086707        14.         4
                              087        N3L02SOO        05-AUG-1998        12:34: 17     29.776778     -88.746118        16.         4
                              088        N3L02SOI        05-AUG-1998        13:34:04      29.660397     -88.692102        20.         4
                              089        N3LO2SO3        05-AUG-1998        15:31:44      29.392483     -88.572582        59.         6
                              090        N3LO2SO5        05-AUG-1998        17:12:04      29.233090     -88.501800        102.        7
                              091        N3LO2SO6        05-AUG-1998        18:15:24      29.173015     -88.472128        191.        12
                              092        N31,02SO8       05-AUG-1998        20:06:52      29@044025     -88.414723        506.        12
                              093        N3LO2SIO        05-AUG-1998        22:14:44      28.879717     -88.340558        955.        12
                              094        N3LOIS07        06-AUG-1998        04:57:69      28.663475     -88.901818        1000.       12
                              095        N3LOIS05        06-AUG-1998        06:59:29      29.806370     -88.949907        504@        12
                              096        NMOIS04         06-AUG-1998        08:33:58      28.897267     -88.975312        198.        12
                              097        NMOIS03         06-AUG-1998        09:38:20      28.979338     -89.004573        81.         7
                              098        N3LOIS01        06-AUG-1998        10:30:16      29.056893     -89.031138        20.         4
                              099        N3MOO01         06-AUG-1998        16:53:10      28.619875     -89.943740        302.        5






                                         Table 3.1.2 Number of bottles sampled by variable on cruise N3.

                            Station       Station        Nutrients      Oxygen        Salinity      Pigments          PM*        POC &
                           Number          Name                                                                                   PON*
                              000      N3TEST04              12             11            12            0              0              0
                              001      NMIIS18               12             12            12            4              3              2
                              002      NMIIS16               12             12            0             0              0              0
                              003      NMIIS14               12             12            0             3              3              2
                              004      N3LIlSI2              12             12            0             0              0              0
                              005      NMIISIO               12             12            0             0              3              2











                                                                                                               17

                           Table 3.1.2 Number of bottles sampled by variable on cruise N3 (continued).

                      Station      Station   Nutrients    Oxygen     Salinity   Pigments     PM*       POC &
                      Number       Name                                                                 PON*
                        006     N3LlIS08         12          12         0           3          3           2
                        007     N31,11S06        5           5          0           0          0           0
                        008     N3LIIS04         5           5          0           3          3           2
                        009     N3LIIS02         5           5          0           3          3           2
                        010     N31,11SOI        4           4          4           0          0           0
                        Oil     N3LIOS01         4           4          4           0          0           0
                        012     N3LIOS03         4           4          0           3          3           2
                        013     N31,10S05        4           4          0           3          3           2
                        014     N31,10S07        4           4          0           2          3           2
                        015     N3LIOS09         5           5          0           0          0           0
                        016     N31,10SH         11          11         0           3          3           2
                        017     N3LIOS13         12          12         0           4          3           2
                        018     N3LIOS15         12          12         0           0          0           0
                        019     N31,10S17        12          12         0           3          3           2
                        020     N31,10S19        11          11         0           0          0           0
                        021     N31,10S21        12          12         12          3          3           2
                        022     N31,09S21        11          11         11          3          2           1
                        023     N3LO9SI9         12          12         0           0          0           0
                        024     N31,09SI7        12          12         0           3          3           2
                        025     N31,09SI5        12          12         0           0          0           0
                        026     N3L09Sl3         12          12         0           3          3           2
                        027     N3L09SlI         12          12         0           0          0           0
                        028     N3LO9SO9         12          12         0           3          3           2
                        029     N31,09SO7        4           4          0           3          3           2
                        030     N3LO9SO5         4           4          0           2          3           2
                        031     N3LO9SO3         4           4          0           2          3           2
                        032     N3LO9SOI         4           4          4           0          0           0
                        033     N3L08S0l         4           4          4           0          0           0
                        034     N3LO8SO3         4           4          0           3          3           2
                        035     N3LO8SO5         4           4          0           0          0           0
                        036     N31,08SO7        12          12         0           3          3           2
                        037     N3L08SO9         11          11         0           3          3           2
                        038     N3L08SlI         12          12         0           0          0           0
                        039     N3L08Sl3         12          12         0           3          3           2
                        040     N3L08Sl5         12          12         0           0          0           0
                        041     N3LO8SI7         12          12         12          3          3           2
                        042     N31,07SI7        12          12         12          3          3           2
                        043     N3L07Sl5         12          12         0           0          0           0
                        044     N3LO7SI3         12          12         0           3          3           2
                        045     N3L07SI1         12          12         0           0          0           0
                        046     N3LO7SO9         11          11         0           0          0           0
                        047     N31,07S07        12          12         0           3          4           2
                        048     N31,07S05        12          12         0           3          4           2
                        049     N31,07SO3        4           4          0           0          0           0
                        050     N31,07SOI        6           6          0           1          3           2
                        051     N31,07SOO        4           4          4           0          0           0
                        052     N3LO6SOI         4           4          4           3          3           2
                        053     N31,06SO3        5           5          0           0          0           0











                   18

                          Table 3.1.2 Number of bottles sampled by variable on cruise N3 (continued).

                      Station     Station    Nutrients   Oxygen      Salinity  Pigments      PM*       POC &
                     Number        Name                                                                PON*
                       054     N3L06SO5          7          7          0           0          0            0
                       055     N3LO6SO7          12         12         0           4          3            2
                       056     N3L06SO9          12         12         0           3          3            1
                       057     N31,06SII         12         12         0           0          0            0
                       058     N3LO6SI3          12         12         0           2          3            2
                       059     N3L06SI5          11         11         0           0          0            0
                       060     N3LO6SI7          12         12         0           0          0            0
                       061     N3L06Sl9          12         12         12          3          3            2
                       062     N31,05SI7         12         12         12          3          3            2
                       063     N3LO5SI5          12         12         0           0          0            0
                       064     N3L05Sl3          12         12         0           3          3            2
                       065     N3L05SlI          12         12         0           0          0            0
                       066     N3L05SO9          12         12         0           3          3            2
                       067     N31,05SO7         12         12         0           0          0            0
                       068     N3LO5SO5          7          7          0           3          3            2
                       069     N3LO5SO3          5          5          0           0          0            0
                       070     N3LO5SOI          4          4          4           2          3            2
                       071     N3LO4SOO          4          4          4           0          0            0
                       072     N3LO4SO1          4          4          0           2          3            2
                       073     N3L04SO3          5          5          0           0          0            0
                       074     N3LO4SO5          6          6          0           0          0            0
                       075     N3LO4SO7          10         10         0           3          3            2
                       076     N31,04SO8         12         12         0           0          3            2
                       077     N3L04SIO          12         12         0           3          3            2
                       078     N3LO4SI2          12         12         12          3          3            2
                       079     N3LO3SIO          12         12         12          3          3            2
                       080     N31,03SO9         12         12         0           3          3            2
                       081     N3LO3SO8          12         12         0           2          3            2
                       082     N3L03SO7          8          8          0           3          3            2
                       083     N3LO3SO5          5          5          0           0          0            0
                       084     N3L03SO3          4          4          0           0          0            0
                       085     N3L03SO1          4          4          0           3          3            2
                       086     N31,03SOO         4          4          4           0          0            0
                       087     N31,02SOO         4          4          4           0          0            0
                       088     N3L02S0l          4          4          0           3          3            2
                       089     N3LO2SO3          6          6          0           0          0            0
                       090     N31,02SO5         7          7          0           2          3            2
                       091     N3LO2SO6          12         12         0           2          3            2
                       092     N3L02SO8          12         12         0           3          3            2
                       093     N3L02SIO          12         12         12          3          3            2
                       094     N3LOIS07          12         12         12          3          3            2
                       095     N3LOIS05          12         12         0           3          3            2
                       096     N3LOIS04          12         12         0           3          3            2
                       097     N31,01S03         7          7          0           6          3            2
                       098     N,3L01S01         4          4          4           3          3            2
                       099     N3MOO01           5          5          5           0          0            0
                    POC = particulate organic carbon; PON particulate organic nitrogen; PM = total particulate material











                                                                                                                                          19

                                       Table 3.1.3 Launch times and locations for XBT drops on cruise N3.

                            Sequence         Station            Date           Time        Latitude      Longitude       Water      Probe
                             Number           Name             (UTC)           (UTC)         (ON)           (1W)         Depth      Type
                                                                                                         -1               (M)
                                001        N3X04O51        26-JUL-1998         18:28:34    29.128542     -87.288903       1000.     T-7
                                002        N3LO5Sl7        26-RJL-1998         19:11:16    29.054498     -87.205215       1000.     T-7
                                003        N3XO5061        26-JUL-1998         20:01:03    28.951487     -87.201157       975.      T-7
                                004        N3X05062        26-RJL-1998         20:58:59    28.810593     -87.218560       984.      T-7
                                005        N3LO6SI9        26-JUL-1998         22:04:35    28.653030     -87.202043       1000.     T-7
                                006        N3X06O71        26-JUL-1998         22:53:18    28.552805     -87.139875       972.      T-7
                                007        N3X06O72        26-JUL-1998         23:43:57    28.448908     -87.063757       996.      T-7
                                008        N31,07SI7       27-JUL-1998         00:26:28    28.376363     -86.982242       1000.     T-7
                                009        N3X0708I        27-Jn-1998          01:28:37    28.303408     -86.842267       1048.     T-7
                                010        N3XO7082        27-JUL- 1998        02:40:32    28.226973     -86.666882       913.      T-7
                                Oil        N31,08SI7       27JUL-1998          03:46:04    28.135313     -86.519485       1000.     T-7
                                012        N3XO8091        27-JUL-1998         04:46:51    28.072010     -86.371352       1009.     T-7
                                013        N3XO8092        27-JUL-1998         05:46:21    28.033502     -86.224763       1744.     T-7
                                014        N3L09S21        27-JUL-1998         06:56:36    28.018862     -86.042678       1001.     T-7
                                015        N3XO9IOl        27-JUL-1998         08:12:15    27.935138     -85.871833       989.      T-7
                                016        N3XO9102        27-JUL-1998         09:12:19    27.865832     -85.733900       989.      T-7
                                017        N3LIOS21        27-JUL-1998         10:05:20    27.782218     -85.631172       996.      T-7
                                018        N3X 10 111      27-JUL-1998         11:05:39    27.666353     -85.540715       1092.     T-7
                                019        N3X1 0 112      27-JUL-1998         11:49:17    27.583952     -85.475033       1071.     T-7
                                020        N3LIlSI7        27-JUL- 1998        14:24:51    27.499863     -85.294733       836.      T-7
                                021        N3LIlSI5        27-JUL-1998         16:25:12    27.499965     -85.145610       630.      T-7
                                022        N3LIISI3        27-JUL-1998         18:33:43    27.499707     -84.985277       388.      T-7
                                023        N3LIISII        27-JUL-1998         21:21:45    27.499983     -84.791900       235.      T-7
                                024        N3LIISO9        27-JUL-1998         23:33:22    27.499763     -84.523500       138.      T-10
                                025        N3LIISO7        28-JUL-1998         02:30:32    27.500060     -84.159797       70.       T-10
                                026        N3LIIS05        28-JUL-1998         05:28:11    27.500192     -83.732703       51.       T-10
                                027        N3LIISO3        28-JUL-1998         08:48:13    27.500408     -83.149598       25.       T-10
                                028        N3LI0SO2        28-JUL-1998         21:14:56    28.559885     -83.186722       16.       T-10
                                029        N3LIOSO4        28-JLTL-1998        23:41:03    28.456135     -83.528418       26.       T-10
                                030        N3LIOSO6        29-JUL-1998         02:05:28    28.342385     -83.882175       35.       T-10
                                031        N3LIOSO8        29-JUL-1998         04:3632     28.227835     -84.240287       49.       T-10
                                033        NMIOSIO         29-JUL- 1998        06:58:35    28.120892     -84.568892       76.       T-10
                                034        N3LIOSI2        29-JUL- 1998        08:50:41    28.048755     -84.799552       ISO.      T-10
                                036        N3LIOS14        29-JUL-1998         10:30:18    27.990537     -84.980543       251.      T-7
                                037        N3LIOSI6        29-JLTL- 1998       12:14:14    27.930118     -85.167112       394.      T-7
                                038        N3LIOSI8        29-JUL- 1998        13:58:30    27.877385     -85.333268       560.      T-7
                                039        N3LIOS2O        29-JUL- 1998        16:30:37    27.813168     -85.517380       763.      T-7
                                040        N3LO9S20        30-JUL-1998         00:29:47    28.073142     -85.951320       809.      T-7
                                041        N3LO9SI8        30-JUL-1998         02:26:32    28.163085     -85.801850       557.      T-7
                                042        N3LO9SI6        30-JUL-1998         04:59:32    28.254307     -85.652963       377.      T-7
                                043        N3LO9SI4        30-JUL-1998         06:50:28    28.361022     -85.479158       242.      T-7
                                044        N3LO9SI2        30-JUL-1998         08:30:39    28.457777     -85.318668       179.      T-10
                                045        N31,09SIO       30-JUL-1998         10:15:27    28.566690     -85.137870       130.      T-10
                                046        N31,09SO8       30-JUL-1998         12:28:12    28.725348     -84.882413       52.       T-10
                                047        N31,09SO6       30-JUL-1998         15:28:03    28.972233     -84.475905       34.       T-10
                                048        N31,09SO4       30-JUL-1998         18:53:45    29.231382     -84.052455       26.       T-10











                       20

                               Table 3.1.3 Launch times and locations for XBT drops on cruise N3 (continued).

                            Sequence         Station            Date            Time        Latitude      Longitude       Water      Probe
                            Number           Name              (UTC)           (UTC)          (ON)           (OW)         Depth      Type
                                                                                                                           (M)
                               049         N3L09SO2        30-JUL-1998        21:37:46      29.427417     -83.728827       16.       T-10
                               050         N3LO8SO2        31-JUL-1998        07:25:51      29.516995     -84.883372       11.       T-10
                               051         N3LO8SO4        31-JUL-1998        09:53:01      29.327487     -85.128430       27.       T-10
                               052         N3LO8SO6        3 1 -JUL- 1998     12:50:42      29.094085     -85.403232       51.       T-10
                               053         N3LO8SO8        31-JUL-1998        15:25:51      28.900722     -85.631332       171.      T-10
                               054         N3LO8SIO        31-JUL-1998        18:12:19      28.705287     -85.859580       258.      T-7
                               055         N3L08SI2        31-JUL-1998        21:12:17      28.496383     -86.105008       378.      T-7
                               056         N3LO8SI4        3 1 -JUL- 1998     23:17:05      28.350663     -86.273215       575.      T-7
                               058         N3LO8SI6        01-AUG-1998        01:26:32      28.216790     -86.445618       823.      T-7
                               059         N3XO7083        01-AUG-1998        04:48:28      28.193288     -86.739348       1304.     T-7
                               060         N3LO7SI6        01-AUG-1998        08:46:48      28.488048     -86.859977       774.      T-7
                               061         N3L07SI4        01-AUG-1998        11:00:30      28.636128     -86.683467       564.      T-7
                               062         N3L07SI2        01-AUG-1998        13:04:23      28.784893     -86.512747       424.      T-7
                               063         N3LO7SIO        01-AUG-1998        15:08:28      28.862688     -86.419637       352.      T-7
                               065         N3LO7SO6        01-AUG-1998        19:32:43      29.251218     -85.977020       160.      T-10
                               066         N3LO7SO4        01-AUG-1998        21:21:58      29.388545     -85.823043       50.       T-10
                               067         N3LO7SO2        01-AUG-1998        23:35:43      29.593712     -85.586452       27.       T-10
                               068         N3LO6SO2        02-AUG-1998        06:24:27      30.098108     -85.954990       30.       T-10
                               069         N3L06SO4        02-AUG-1998        08:00:17      29.940802     -86.088962       39.       T-10
                               070         N3LO6SO6        02-AUG-1998        10:00:28      29.760210     -86.247113       68.       T-10
                               071         N3LO6SO8        02-AUG-1998        12:26:07      29.600152     -86.384920       135.      T-10
                               073         N3LO6SIO        02-AUG-1998        14:46:50      29.409880     -86.548825       289.      T-7
                               074         N3LO6SI2        02-AUG-1998        17:29:36      29.226262     -86.706575       438.      T-7
                               075         N3LO6SI4        02-AUG-1998        20:20:13      29.047830     -86.860465       559.      T-7
                               076         N3LO6SI6        02-AUG-1998        22:22:38      28.911722     -86.979190       681.      T-7
                               077         N3LO6SI8        03-AUG-1998        00:45:00      28.742548     -87.124970       761.      T-7
                               078         N3L05SI8        03-AUG-1998        03:59:36      28.817380     -87.351317       1279.     T-7
                               079         N3LO5SI6        03-AUG-1998        09:08:22      29.181633     -87.148533       823.      T-7
                               080         N3LO5SI4        03-AUG-1998        11:22:03      29.374378     -87.055072       613.      T-7
                               081         N3L05S12        03-AUG-1998        13:25:43      29.534155     -86.977733       346.      T-7
                               082         N3L05S10        03-AUG-1998        14:52:20      29.671867     -86.913882       221.      T-7
                               083         N3LO5SO8        03-AUG-1998        16:41:59      29.808145     -86.846108       167.      T-10
                               084         N3LO5SO6        03-AUG-1998        18:24:12      29.959968     -86.773190       123.      T-10
                               085         N3LO5SO4        03-AUG-1998        20:28:15      30.111905     -86.699738       47.       T-10
                               086         N3L05SO2        03-AUG-1998        22:03:49      30.204203     -86.654452       28.       T-10
                               087         N3LO4SO2        04-AUG-1998        04:46:51      30.102758     -87.351113       29.       T-10
                               088         N3LO4SO4        04-AUG-1998        06:45:25      29.856718     -87.351235       46.       T-10
                               089         N3LO4SO6        04-AUG-1998        08:29:03      29.656727     -87.350628       80.       T-10
                               090         N3LO4SO9        04-AUG-1998        11:16:26      29.449588     -87.350223       360.      T-7
                               092         N3L04SII        04-AUG-1998        13:48:22      29.275227     -87.355148       779.      T-7
                               093         N3XO3042        04-AUG-1998        16:34:25      29.238290     -87.494077       943.      T-7
                               094         N3X03051        04-AUG-1998        18:02:47      29.127193     -87.600058       1284.     T-7
                               096         N3XO3041        04-AUG-1999        19:25:43      29.199075     -87.702525       1038.     T-7
                               097         N3LO3SO6        05-AUG-1998        02:26:25      29.453147     -87.927437       62.       T-10
                               098         N3LO3SO4        05-AUG-1998        04:05:44      29.678190     -87.972005       40.       T-10
                               099         N3LO3SO2        05-AUG-1998        06:04:31      29.912645     -88.014382       34.       T-10











                                                                                                                                     21

                              Table 3.1.3 Launch times and locations for XBT drops on cruise N3 (continued).

                            Sequence       Station           Date          Time        Latitude     Longitude     Water       Probe
                            Number         Name             (UTQ           (UTQ          (ON)          (OW)       Depth       Type
                                                                                                                    (M)
                              100        N3LO2SO2       05-AUG-1998       14:30:03    29.538337     -88.636545      30.       T-10
                              101        N3LO2SO4       05-AUG-1998       16:25:55    29.316452     -88.536933      65.       T-10
                              102        N3LO2SO7       05-AUG-1998       19:22:47    29.122027     -88.451720      293.      T-10
                              103        N3LO2SO9       05-AUG-1998       21:36:10    28.955270     -88.377165      881.      T-7
                              104        N3XO1022       06-AUG-1998       00:45:25    28.798690     -88.556007      1024.     T-7
                              105        N3XO1021       06-AUG-1998       01:59:36    28.742565     -88.758103      994.      T-7
                              106        N3XO1023       06-AUG-1998       03:55:34    28.590807     -88.747148      1284.     T-7
                              109        N3LOIS06       06-AUG-1998       06:25:17    28.744000     -88.926665      734.      T-7
                              110        N3LOIS02       06-AUG-1998       10:08:09    29.017445     -89.017360      55.       T-10


                      Launches at missing sequence numbers were failures or deemed bad data during QA/QC, except
                      numbers 32 and 72, which had no XBT launch although the counter advanced.




                      3.1.2 Cruise N4


                      The fourth NEGOM-COH hydrography cruise (M) was conducted aboard the RIV Gyre 13-24
                      November 1998. It was staged out of Gulfport, MS, and returned to Galveston, TX Dr.
                      Douglas C. Biggs and Dr. Norman L. Guinasso, Jr., were co-chief scientists. Ninety-nine CTD
                      stations, including one test station, were completed and 122 XBT drops were made. The CTD
                      and XBT locations and the cruise track- are shown in Figure 3.1.2. The test station was taken
                      approximately at the location of the seawardmost CTD station on line 4. The cruise track starts
                      at this location and runs along the 1000-m isobath to the seawardmost station on line I I where
                      the CTD/XBT station series began. XBTs were dropped along this 1000-m track. Only the
                      locations of the 112 successful XBT drops are shown in Figure 3.1.2. Station number, date,
                      time, location, water depth, and number of bottles tripped at each CTD station are shown in
                      Table 3.1.4.


                      Stations at which bottle samples were taken are summarized in Table 3.1.5. Nutrient and
                      oxygen concentrations were measured from every Niskin bottle depth sampled. Salinity was
                      measured at all bottles only at the most shoreward and most offshore stations and at the test
                      station for a total of 23 stations. Pigment measurements were collected at the top bottle, the
                      chlorophyll-maximum as determined by the downcast fluorescence trace, and the low light
                      regime immediately below the chlorophyll-maximum at 59 stations. PM, POC, and PON were
                      measured from the top and bottom bottles and, for PM, from a middle, "clear water" bottle at
                      60 stations.


                      Location, date, time, total water depth, and probe type of the 112 successful, XBT drops are
                      listed in Table 3.1.6. Due to instrument malfunction, continuous ADCP data were collected


















                       31 *N








                       30*N
                                 W7


                                                                                                                gg -


                                                                                                                           C, "AWA,
                                                                                                                                MR,
                       29-N                            3      5
                                                                                                                         CAR
                                                 2
                                                                                                                              P-P

                                                              6


                                                                 7

                       28*N
                                                                             9
                                        * CTDIBottle - 98 Stations
                                                                                 10
                                        * XBT - 112 Stations





                       27*N
                         90*W         89*W         88*W         87*W        86*W         95*W         84*W         93*W         82*W




                     Figure 3.1.2. Station locations for cruise N4 conducted 13 -24 November 1998. CTD stations began with the most
                                  seaward station on line 11. The thick line shows the cruise track, which began at the location of the most
                                  seaward station on line 4.




                                  a                      - 011@ go, so:
                                   @ 0, go, Ow











                                                                                                                                         23

                        only along the survey tracks of lines I through 4 (Section 3.2.3). Flow-through, near-surface
                        temperature, conductivity, and fluorescence were logged every 2 min (Section 3.2.5). Surface
                        samples were analyzed for chlorophyll a to calibrate the flow-through fluorometer at 108
                        locations.

                        Five complementary research efforts were accommodated on autumn cruise N4. Twenty-four
                        ARGOS-tracked drifters were launched for Dr. James M. Price of MMS. A marine mammal
                        survey was conducted by Joel Ortega-Ortiz, Elizabeth Zuniga, and Todd Speakman, graduate
                        students at TAMU-Galveston. The data from this and the three previous surveys will be the
                        basis for Mr. Ortega-Ortiz's Ph.D. dissertation. Plankton net tows were made at the 12 stations
                        closest to the moored upward-looking ADCP current meters in DeSoto Canyon for Rebecca
                        Scott's M.S. thesis research on correlation of standing stocks of zooplankton and micronekton
                        with volume backscatter from moored ADCPs. Dr. Caesar Fuentes-Vaco and Mr. Joe
                        Vanderbloemen of the USF Remote Sensing Laboratory continued the USF bio-optical
                        measurements of downwelling and sea-leaving radiance, For this "sea truth" for the SeaWiFS
                        satellite receiver, they made vertical profiles twice daily about 1000-1100 and 1400-1600 local
                        time, using USF's multichannel Marine Environmental Radiometer. They also used a WetLabs
                        AC-9 bio-optical profiler for an underway survey of wavelength-specific absorbance. This
                        instrument measures the absorbance spectrum (action spectrum) of chlorophylls and accessory
                        pigments in the same nine wavelength bands being monitored by the SeaWiFS satellite in low
                        earth orbit. - The mooring that Ms. Cheryl Burden, TAMU, had deployed during N3 in
                        Mississippi Canyon was successfully recovered on the transit back to Galveston at the end of
                        N4. Further information on these complementary research programs can be obtained from the
                        scientists involved.





                                          Table 3.1.4. Times and positions for CTD stations on cruise N4.


                            Station        Station            Date          Time        Latitude      Longitude      Depth     No. of
                            Number         Name              (UTC)          (UTC)         (ON)           (OW)          (m)     Bottles
                              000        N4TEST04        13-NOV-1998       18:40:28     29.195558     -87.349935       986.        12
                              001        N41,11SI8       14-NOV-1998       17:29:10     27.499188     -85.393045       996.        10
                              002        N4LIIS16        14-NOV-1998       19:53:42     27.500687     -85.225825       754.        12
                              003        N4LllSl4        14-NOV-1998       21:39:45     27.501593     -85.075830       495.        12
                              004        N4LIlSI2        14-NOV-1998       23:29:17     27.500265     -84.889595       298.        11
                              005        N4LIISIO        15-NOV-1998       01:26:32     27.499510     -84.681945       202.        12
                              006        N4LllS08        15-NOV-1998       04:00:42     27.500248     -84.343957       102.        12
                              007        N4LIIS06        15-NOV-1998       06:59:06     27.499490     -83.944130       58.         4
                              008        N41, I I S04    15-NOV-1998       10:06:06     27.501452     -83.497440       43.         4
                              009        N4L I I S02     15-NOV-1998       13:13:58     27.500517     -83.023298       22.         4
                              010        N41,11SOI       15-NOV-1998       14:36:00     27.497833     -82.837300       13.         3
                              Oil        N4LIOS01        15-NOV-1998       23:13:29     28.607022     -83.056033       11.         4
                              012        N4LIOS03        16-NOV-1998       01:19:17     28.522183     -83.329223       21.         4











                       24

                                 Table 3.1.4. Times and positions for CTD stations on cruise N4 (continued).


                           Station        Station             Date           Time        Latitude      Longitude       Depth      No. of
                           Number          Name              (UTC)          (UTC)          (ON)           (OW)           (m)      Bottles
                              013        N4LIOS05        16-NOV-1998        04:05:15     28.400337     -83.701557        32.         6
                              014        N4LIOS07        16-NOV-1998        06:44:45     28,285638     -84.058747        39.         5
                              015        N4LIOS09        16-NOV-1998        09:13:58     28.177663     -84.403115        60.         6
                              016        N4LIOS11        16-NOV-1998        11:36:49     28,078403     -84.706477        100.        12
                              017        N4LIOS13        16-NOV-1998        13:13:11     28.023447     -84.877337        200.        12
                              018        N4LIOS15        16-NOV-1998        15:08:19     27,959290     -85.071193        313.        12
                              019        N4LIOS17        16-NOV-1998        17:09:14     27.895093     -85.277087        496.        12
                              020        N4LIOS19        16-NOV-1998        19:49:55     27.852677     -85.412360        655.        12
                              021        N4LIOS21        16-NOV-1998        21:18:31     27.784385     -85.629952        989.        12
                              022        N4L09S21        17-NOV-1998        02:03:28     28,018665     -86.042477        994.        12
                              023        N4L09SI9        17-NOV-1998        04:22:46     28,115573     -85.876378        681.        12
                              024        N4L09SI7        17-NOV-1998        06:14:33     28,189903     -85.752475        505.        12
                              025        MUMS            17-NOV-1998        08:33:01     28,311012     -85.562162        304.        12
                              026        N4L09SI3        17-NOV-1998        10:32:39     28.409955     -85.395780        201.        12
                              027        N4L09SII        17-NOV-1998        12:21:30     28.508060     -85.236110        164.        12
                              028        N4L09SO9        17-NOV-1998        14:22:02     28.626885     -85.044172        98.         6
                              029        N4L09SO7        17-NOV-1998        17:15:41     2&838068      -84.693530        46.         6
                              030        N4L09SO5        17-NOV-1998        21:31:51     29.104647     -84.257842        28.         7
                              031        N4L09SO3        18-NOV-1998        00:55:00     29,341840     -83.860275        20.         5
                              032        N4LO9SOI        18-NOV-1998        03:12:26     29.517672     -83.583102        '10.        4
                              033        N4L08SOI        18-NOV-1998        10:32:50     29.621488     -84.786358        8.          3
                              034        N4L08SO3        18-NOV-1998        12:59:56     29.391728     -85.043183        22.         5
                              035        N4L08SO5        18-NOV-1998        15:08:24     29.203762     -85.273923        40.         6
                              036        N4L08SO7        18-NOV-1998        17:37:25     28.983717     -85.530202        136.        12
                              037        N4L08SO9        18-NOV-1998        20:11:33     28.825705     -85.718520        199.        12
                              038        N4L08SII        18-NOV-1998        23:00:34     28.605965     -85.976177        309.        12
                              039        N4LO8SI3        19-NOV-1998        01:34:39     28.402092     -86.213295        496.        12
                              040        N4L08SI5        19-NOV-1998        03:20:50     28.296498     -86.340252        672.        12
                              041        N4L08SI7        19-NOV-1998        05:39:35     28.139142     -86.525590        978.        12
                              042        N4L07SI7        19-NOV-1998        11:00:18     28.378317     -86.983005        991.        12
                              043        N4L07SI5        19-NOV-1998        13:45:16     28.558288     -86.775057        669.        12
                              044        N4L07SI3        19-NOV-1998        15:51:19     28.701112     -86.613103        500.        12
                              045        N4L07SII        19-NOV-1998        18:05:37     28.864333     -86.421905        381.        12
                              046        N4LO7SO9        19-NOV-1998        20:21:01     29.017980     -86.245900        316.        12
                              047        N4L07SO7        19-NOV-1998        22:41:05     29.209330     -86.027185        200.        12
                              048        N4L07SO5        19-NOV-1998        23:59:11     29.300757     -85@917322        88.         12
                              049        N4L07SO3        20-NOV-1998        02:07:53     29.500063     -85.693453        32.         6
                              050        N4L07SOI        20-NOV-1998        04:13:22     29,686317     -85.478558        21.         4
                              051        N4L07SOO        20-NOV-1998        05:08:12     29.739055     -85.418357        11.         3
                              052        N4L06SOI        20-NOV-1998        09:33:09     30,179043     -85.884057        21.         4
                              053        N4L06SO3        20-NOV-1998        11:10:12     30.018510     -86.022023        32.         5
                              054        N4LO6SO5        20-NOV-1998        12:47:33     29,851515     -86.166228        47.         6
                              055        N4L06SO7        20-NOV-1998        14:24:36     29,686430     -86.312373        100.        12
                              056        N4L06SO9        20-NOV-1998        16:42: 10    29.500223     -86.471882        203.        12
                              ,057       N4L06SII        20-NOV-1998        19:05:50     29,314793     -86.630258        382.        12
                              058        N4L06SI3        20-NOV-1998        21:32:05     29@  134022   -86.788912        498.        12
                              059        N4L06SI5        20-NOV-1998        23:34:15     2&983260      -86.915318        610.        12











                                                                                                                                            25

                                   Table 3.1.4. Times and positions for CTD stations on cruise N4 (continued).


                             Station        Station            Date            Time       Latitude       Longitude       Depth     No. of
                            Number          Name              (UTC)           (UTC)          (ON)           (OW)           (m)     Bottles
                               060        N4LO6SI7        21-NOV-1998         01:33:45    28.827043      -87.052378        768.        12
                               061        N4LO6SI9        21-NOV-1998         03:47:56    28.653253      -87.202562        999.        12
                               062        N4L05SI7        21-NOV-1998         07:20:37    29.054417      -87.205243        997.        12
                               063        N4LO5SI5        21-NOV-1998         09:59:21    29.273453      -87.105488        709.        12
                               064        N4L05SI3        21-NOV-1998         12:19:15    29.468407      -87.012885        480.        12
                               065        N4L05SII        21-NOV-1998         14:30:50    29.610092      -86.943343        261.        12
                               066        N4LO5SO9        21-NOV-1998         15:53:03    29.724592      -86.885620        199.        12
                               067        N4L05SO7        21-NOV-1998         17:50:00    29.881287      -86.811973        148.        12
                               068        N4L05SO5        21-NOV-1998         19:21:36    30.028600      -86.739370        100.        12
                               069        N4LO5SO3        21-NOV-1998         21:13:08    30.204423      -86.656528        31.         5
                               070        N4LO5SOI        21-NOV-1998         22:38:55    30.365618      -86.579485        20.         4
                               071        N4LO4SOO        22-NOV-1998         06:38:44    30.294032      -87.353068        8.          2
                               072        N4L04SOI        22-NOV-1998         07:22:35    30.221478      -87.353522        21.         4
                               073        N4LO4SO3        22-NOV-1998         09:21:07    29.978903      -87.353180        30.         4
                               074        N4L04SO5        22-NOV-1998         11:27:56    29.729947      -87.351290        77.         6
                               075        N4LO4SO7        22-NOV-1998         13:03:13    29.567627      -87.354602        104.        12
                               076        N4L04SO8        22-NOV-1998         14:05:55    29.530745      -87.350418        218.        12
                               077        N4LO4SIO        22-NOV-1998         15:47:59    29.373837      -87.333593        514.        12
                               078        N4LO4S12        22-NOV-1998         18:24:39    29.193152      -87.352120        1001.       12
                               079        N41,03SIO       22-NOV-1998         23:40:13    29.157167      -87.864602        971.        12
                               080        N41,03SO9       23-NOV-1998         01:32:52    29.202467      -87.891375        524.        12
                               081        N4L03SO8        23-NOV-1998         02:51:26    29.284967      -87.890168        192.        12
                               082        N4L03SO7        23-NOV-1998         03:53:16    29.344007      -87.884107        95.         12
                               083        N4L03SO5        23-NOV-1998         06:13:31    29.559247      -87.948640        42.         6
                               084        N4L03SO3        23-NOV-1998         08:40:06    29.803355      -87.999593        37.         5
                               085        N4L03SOI        23-NOV-1998         10:47:28    30.029165      -88.025323        21.         5
                               086        N4L03SOO        23-NOV-1998         11:56:57    30.143037      -88.088907        14.         3
                               087        N41,02SOO       23-NOV-1998         16:51:53    29.787698      -88.753917        15.         3
                               088        N4L02SOI        23-NOV-1998         17:59:31    29.660398      -88.691945        19.         5
                               089        N4L02SO3        23-NOV-1998         20:25:31    29.393723      -88.574518        58.         7
                               090        N4L02SO5        23-NOV-1998         @1:56:54    29.231942      -88.503993        102.        12
                               091        N4L02SO6        23-NOV-1998         22:59:52    29.175060      -88.473368        188.        12
                               092        N4L02SO8        24-NOV-1998         00:32:37    29.047563      -88.415242        492.        12
                               093        N4L02SIO        24-NOV-1998         02:40:14    28.879962      -88.340457        969.        12
                               094        N4LOIS07        24-NOV-1998         07:46:56    28.663585      -88.900753        997.        12
                               095        N4LOIS05        24-NOV-1998         09:52:30    28.805485      -88.948545        503.        12
                               096        N4LOIS04        24-NOV-1998         11:18:56    28.895372      -88.976230        202.        12
                               097        N4LOIS03        24-NOV-1998         12:18:45    28.952748      -88.999563        102.        12
                               098        N4LOIS01        24-NOV-1998         13:34:36    29.058608      -89.030117        19.         4











                   26

                                 Table 3.1.5 Number of bottles sampled by variable on cruise N4.

                      Station     Station    Nutrients   Oxygen      Salinity   Pigments     PM*       POC &
                      Number      Name                                                                  PON*
                        000      N4TEST04        12          23          12         0           0         0
                        001      N41,11S18       10          10          10         3           3         2
                        002      N41,11S16       12          12          0          0           0         0
                        003      N4LllSl4        12          12          0          3           3         2
                        004      N4LllSl2        I I         11          0          0           0         0
                        005      N41,11SIO       12          12          0          3           3         2
                        006      N4LIIS08        12          12          0          3           3         2
                        007      N4LlIS06        4           4           0          0           0         0
                        008      N4L I I S04     4           4           0          2           3         2
                        009      N4LlIS02        4           4           0          2           2         2
                        010      N4LllS0l        3           3           3          0           0         0
                        Oil      N41,10SOI       4           4           4          0           0         0
                        012      N4LIOS03        4           4           0          2           3         2
                        013      N41,10S05       6           6           0          2           3         2
                        014      N4LIOS07        5           5           0          0           3         2
                        015      N41,10S09       6           6           0          0           0         0
                        016      N41,10SIl       12          12          0          0           3         2
                        017      N4LIOS13        12          12          0          3           3         2
                        018      N41,10S15       12          12          0          0           0         0
                        019      N4LIOS17        12          12          0          3           3         2
                        020      N41,10S19       12          12          0          0           0         0
                        021      N4LIOS21        12          12          12         3           3         2
                        022      N41,09S21       12          12          12         3           3         2
                        023      N41,09SI9       12          12          0          0           0         0
                        024      N41,09SI7       12          12          0          3           3         2
                        025      N4L09Sl5        12          12          0          0           0         0
                        026      N4L09SI3        12          12          0          3           3         2
                        027      N41,09SII       12          12          0          0           0         0
                        028      N41,09SO9       6           6           0          3           3         2
                        029      N4LO9SO7        6           6           0          3           3         2
                        030      N41,09SO5       7           7           0          3           3         2
                        031      N41,09SO3       5           5           0          2           3         2
                        032      N41,09SOI       4           4           4          2           0         0
                        033      N4L08S0l        3           3           3          0           0         0
                        034      N41,08SO3       5           5           0          3           3         2
                        035      N41,08SO5       6           6           0          0           0         0
                        036      N4L08SO7        12          12          0          3           3         2
                        037      N4LO8SO9        12          12          0          3           3         2
                        038      N4L08Sll        12          12          0          0           0         0
                        039      N4L08SI3        12          12          0          3           3         2
                        040      N41,08SI5       12          12          0          0           0         0
                        041      N4L08Sl7        12          12          12         3           3         2
                        042      N41,07SI7       12          12          12         3           3         2
                        043      N41,07SI5       12          12          0          0           0         0
                        044      N41,07S13       12          12          0          3           3         2
                        045      N4L07Sll        12          12          0          0           0         0











                                                                                                            27

                          Table 3.1.5 Number of bottles sampled by variable on cruise N4 (continued).

                      Station    Station    Nutrients   Oxygen     Salinity   Pigments     PM*      POC &
                     Number       Name                                                               PON*
                        046     N4LO7SO9         12        12         0          0          0          0
                        047     N4LO7SO7         12        12         0          3          3          2
                        048     N4LO7SO5         12        12         0          3          3          2
                        049     N4LO7SO3         6         6          0          0          0          0
                        050     N4LO7SOI         4         4          0          2          3          2
                        051     N4LO7SOO         3         3          3          0          0          0
                        052     N4L06SOI         4         4          4          2          3          2
                        053     N4L06SO3         5         5          0          0          0          0
                        054     N4L06SO5         6         6          0          0          0          0
                        055     N4L06SO7         11        12         0          3          3          2
                        056     N4L06SO9         12        12         0          3          3          2
                        057     N4L06SII         12        12         0          0          0          0
                        058     N4L06SI3         12        12         0          3          3          2
                        059     N4LO6SI5         12        12         0          0          0          0
                        060     N4L06SI7         12        12         0          0          0          0
                        061     N4L06SI9         12        12         12         3          3          2
                        062     N4L05SI7         12        12         12         3          3          2
                        063     N4LO5SI5         12        12         0          0          0          0
                        064     N4L05SI3         12        12         0          3          3          2
                        065     N4L05SII         12        12         0          0          0          0
                        066     N4LO5SO9         12        12         0          3          3          2
                        067     N4L05SO7         12        12         0          0          0          0
                        068     N4LO5SO5         12        12         0          3          3          2
                        069     N41,05SO3        5         5          0          0          0          0
                        070     N4L05SOI         4         4          4          2                     2
                        071     N4LO4SOO         2         2          2          0          0          0
                        072     N4L04SOI         4         4          0          3          3          2
                        073     N4LO4SO3         4         4          0          0          0          0
                        074     N4L04SO5         6         5          0          0          0          0
                        075     N4L04SO7         12        12         0          3          3          2
                        076     N4L04SO8         12        12         0          3          3          2
                        077     N41,04SIO        12        11         0          3          3          2
                        078     N4L04SI2         12        12         12         3          3          2
                        079     N4LO3SIO         12        12         12         3          3          2
                        080     N4L03SO9         12        12         0          3          3          2
                        081     N4L03SO8         12        12         0          2          3          2
                        092     N4L03SO7         12        12         0          3          3          2
                        083     N4L03SO5         6         6          0          0          0          0
                        084     N4LO3SO3         5         5          0          0          0          0
                        085     N4L03SOI         5         5          0          3          3          2
                        086     N4LO3SOO         3         3          3          0          0          0
                        087     N4L02SOO         3         3          3          0          0          0
                        088     N4LO2SOI         5         5          0          2          2          2
                        089     N4LO2SO3         7         7          0          0          0          0
                        090     N,4L02SO5        12        12         0          3          3          2
                        091     N4LO2SO6         12        12         0          3          3          2











                      28

                                 Table 3.1.5 Number of bottles sampled by variable on cruise N4 (continued).

                          Station         Station      Nutrients      Oxygen         Salinity    Pigments        PM*          POC &
                          Number          Name                                                                                 PON*
                             092       N41,02SO8           12            12            0             3              3              2
                             093       N4L02SIO            12            12            12            3              3              2
                             094       N4LOIS07            12            12            12            3              3              2
                             095       N4LOIS05            12            12            0             3              3              2
                             096       N41,01S04           12            12            0             2              3              2
                             097       N4LOIS03            12            12            0             2              3              2
                             098       N4LOIS01            4             4             4             2              3              2


                        PM = total particulate material; POC             particulate organic carbon; PON            particulate organic
                         nitrogen





                                     Table 3.1.6 Launch times and locations for XBT drops on cruise N4.


                          Sequence         Station           Date            Time         Latitude      Longitude      Water Probe
                          Number           Name              (UTC)            (UTC)         (ON)           (OW)         Depth      Type
                                                                                                                         (M)
                             001          N4L05SI7       13-NOV-1998        21:27:56      29.051453     -87.200103       997.      T-7
                             002          N4XO506M       13-NOV-1998        22:50:36      28.888602     -87.210342       1324.     T-7
                             003          N41,06SI9      14-NOV-1998        00:41:52      28.652912     -87.202508       1001.     T-7
                             004          N4X0607M       14-NOV-1998        02:04:57      28.501637     -87.102462       967.      T-7
                             005          N41,07S17      14-NOV-1998        03:30:41      28.334495     -86.975843       1048.     T-7
                             006          N4X0708M       14-NOV-1998        07:16:43      28.216532     -86.668467       1019.     T-7
                             007          N4LO8SI7       14-NOV-1998        08:21:43      28.138928     -86.524803       991.      T-7
                             008          N4XO809M       14-NOV-1998        09:54:49      28.058220     -86.303430       1006.     T-7
                             009          N41,09S21      14-NOV-1998        11:34:58      28.019368     -86.042663       998.      T-7
                             010          N4X09l0M       14-NOV-1998        13:15:37      27.905900     -85.814612       992.      T-7
                             Oil          N4LIOS21       14-NOV-1998        14:46:43      27.782853     -85.630730       1015.     T-7
                             012          N4XIO11M       14-NOV-1998        16:13:04      27.627328     -85.500132       1156.     T-7
                             013          N4LllS17       14-NOV-1998        19:20:15      27.500167     -85.294667       835.      T-7
                             014          N41,11S15      14-NOV-1998        21:08:23      27.500033     -85.145808       624.      T-7
                             015          NCIIS13        14-NOV-1998        22:48:48      27.499995     -84.985853       391.      T-7
                             016          N4LllSIl       15-NOV-1998        00:39:54      27.499772     -84.791605       235.      T-7
                             017          N4LllS09       15-NOV-1998        02:50:31      27.499770     -84.523337       138.      T-10
                             018          N41,11S07      15-NOV-1998        05:29:37      27.499973     -84.159748       70.       T-10
                             019          N4LlIS05       15-NOV-1998        08:33:59      27.503267     -83.730715       40.       T-10
                             020          N4LllS03       15-NOV-1998        11:45:44      27.499905     -83.149712       34.       T-10
                             021          N41,10S02      16-NOV-1998        00:15:46      28.559937     -83.186537       16.       T-10
                             022          N41,10S04      16-NOV-1998        02:51:36      28.455878     -83.528225       26.       T-10
                             023          N4LIOS06       16-NOV-1998        05:31:26      29.342523     -83.882147       36.       T-10
                             024          N4LIOS08       16-NOV-1998        08:04:48      28.227573     -84.240312       49.       T-10
                             025          N4LIOSIO       16-NOV-1998        10:33:30      28.122690     -84.567622       74.       T-10
                             026          N4LIOS12       16-NOV-1998        12:36:25      28.048803     -84.799295       149.      T-10











                                                                                                                                            29

                                Table 3.1.6 Launch times and locations for XBT drops on cruise N4 (continued).


                           Sequence         Station             Date            Time         Latitude      Longitude      Water Probe
                            Number           Name              (UTC)            (UTC)          (-N)           (OW)        Depth        Type
                                                                                                                            (M)  '
                               027         N4LIOS14        16-NOV-1998         14:17:19      27.991400     -84.976102       248.       T-7
                               028         N4LIOS16        16-NOV-1998         16:16:47      27.930648     -85.167167       391.       T-7
                               029         N4LIOS18        16-NOV-1998         18:08:49      27.877398     -85.333218       564.       T-7
                               030         N4LIOS20        16-NOV-1998         20:22:48      27.812882     -85.517523       789.       T-7
                               032         N4L09SI8        17-NOV- 1998        05:44:44      28,165895     -85.798737       554.       T-7
                               033         N4L09SI6        17-NOV-1998         07:43:01      28,253497     -85.651273       376.       T-7
                               034         N4L09S14        17-NOV-1998         09:45:28      28.359870     -85.478398       242.       T-7
                               035         N4L09SI2        17-NOV- 1998        11:36:34      28.457990     -85.318902       177,       T-10
                               036         N4LO9SIO        17-NOV-1998         13:32:24      28.567338     -85.138578       130.       T-10
                               037         N4LO9SO8        17-NOV-1998         15:44:58      28.723967     -84.881628       51.        T-10
                               038         N4L09SO6        17-NOV-1998         19.-45:19     28.971638     -84.475792       35.        T-10
                               039         N4L09SO4        17-NOV-1998         23:23:31      29.230332     -84.051905       25.        T-10
                               040         N4L09SO2        18-NOV-1908         02:02:07      29.427802     -83.728225'      16.        T-10
                               041         N4LO8SO2        18-NOV-1998         11:27:27      29.533032     -84.887430       15.        T-10
                               042         N4LO8SO4        18-NOV-1998         13:48:52      29.327933     -85.127905       27.        T-10
                               043         N4L08SO6        18-NOV-1998         16:23:40      29.094000     -85.403107       50.        T-10
                               044         N4L08SO8        18-NOV-1998         19:20:31      28.901185     -85,628572       171.       T-10
                               045         N4LO8SIO        18-NOV-1998         21:52:18      28.709730     -85.854008       257.       T-7
                               046         N4LO8SI2        19-NOV-1998         00:31:31      28.496517     -86.104368       377.       T-7
                               047         N4LO8SI4        19-NOV-1998         02:42:40      28.347338     -86.277458       579.       T-7
                               048         N4L08SI6        19-NOV-1998         04:48:25      28.220515     -86.433368       830.       T-7
                               049         N4L07SI6        19-NOV-1998         12:55:20      28.481910     -86.860967       778.       T-7
                               050         N4L07S@14       19-NOV-1998         15:10:30      28.635562     -86.683107       568.       T-7
                               051         N4L07SI2        19-NOV-1998         17:12:53      28.785827     -86.513977       426.       T-7
                               053         N4L07SIO        19-NOV-1998         19:34:58      28.945643     -86.330227       341.       T-7
                               054         N4L07SO8        19-NOV-1998         21:50:50      29.121622     -86.128088       257.       T-7
                               055         N4L07SO6        19-NOV-1998         23:26.23      29.251247     -85.978628       156.       T-10
                               056         N4L07SO4        20-NOV-1998         01:01:48      29.390873     -85.819592       49.        T-10
                               057         N4L07SO2        20-NOV-1998         03:13:42      29.599240     -85.589752       28,        T-10
                               058         N4L06SO2        20-NOV-1998         10:25:19      30.098537     -85.954987       30.        T-10
                               059         N4L06SO4        20-NOV-1998         11:57:42      29.942285     -86.090355       40.        T-10
                               060         N4L06SO6        20-NOV-1998         13:42:45      29.759522     -86.246462       67.        T-10
                               061         N4L06SO8        20-NOV-1998         15:47:20      29.600135     -86.385422       131        T-10
                               062         N4L06SIO        20-NOV-1998         18:11:39      29.410135     -86.549065       289.       T-7
                               063         N4L06SI2        20-NOV-1998         20:39:57      29.225410     -86.707590       440,       T-7
                               064         N4L06SI4        20-NOV-1998         22:55:40      29.048713     -86.861013       561.       T-7
                               065         N4L06SI6        21-NOV-1998         00:49:16      28.908973     -86.982213       678.       T-7
                               066         N4L06SI8        21-NOV-1998         03:00:59      29.742583     -87.125000       04.        T-7
                               067         N4L05SI6        21-NOV-1998         08:44:14      29.121247     -87.175728       936.       T-7
                               068         N4L05SI6        21-NOV-1998         09:11:20      29.181695     -87.149200       825.       T-7
                               069         N4L05SI5        21-NOV-1998         09:32:06      29.227092     -87.127435       769.       T-7
                               070         N4LO5SI4        21-NOV-1998         11:07:00      29.324433     -87.077803       654.       T-7
                               071         N4L05SI4        21-NOV-1998         11:30:27      29.374575     -87.056032       615.       T-7
                               072         N4L05SI3        21-NOV-1998         11:55:11      29.427335     -87.029223       559.       T-7
                               075         N4L05SI2        21-NOV-1998         13:36:23      29.505705     -86.979567       39L        T-7











                       30

                              Table 3.1.6 Launch times and locations for XBT drops on cruise N4 (continued).


                          Sequence         Station            Date            Time        Latitude      Longitude      Water Probe
                           Number          Name              (UTC)           (UTC)           (ON)          (OW)         Depth      Type
                                                                                                                         (M)
                              076        N4LO5SI2        21-NOV-1998         13:50:21     29.534910     -86.978842       342.      T-7
                              077        N4L05S1I        21-NOV-1.998        14:08:10     29.570957     -86.960240       295.      T-7
                              078        N4LO5SIO        21-NOV-1998         15:  06:11   29.635217     -86.930740       242.      T-7
                              080        N4L05SIO        21-NOV-1998         15:22:46     29.670008     -86.913655       221.      T-7
                              081        N4L05SO9        21-NOV-1998         15:35:38     29.697105     -86.900238       209.      T-7
                              082        N4L05'SO8       21-NOV-1998         16:50:01     29.763163     -86.868973       184.      T-10
                              083        N4L05SO8        21-NOV-1998         17:10:44     29.806645     -86.847918       164.      T-10
                              084        N4L05SO7        21-NOV-1998         17:27:26     29.843128     -86.831553       159.      T-10
                              085        N4L05SO6        21-NOV-1998         18:27:16     29.918045     -86.794725       135.      T-10
                              086        N4L05SO6        21-NOV-1998         18:46:03     29.959785     -86.774023       123.      T-10
                              087        N4LO5SO5        21-NOV-1998         19:02:15     29.996123     -86.756542       111.      T-10
                              088        N4L05SO4        21-NOV-1998         20:11:48     30.078303     -86.721527       63.       T-10
                              089        N4LO5SO4        21-NOV-1998         20:27:34     30.115220     -86.707953       46.       T-10
                              091        N4LO5SO3        21-NOV-1998         20:48:20     30.160305     -86.678328       32.       T-10
                              092        N4L05SO2        21-NOV-1998o        21:41:07     30.242047     -86.637325       24.       T-10
                              093        N4LO5SO2        21-NOV-1998         21:59:18     30.283565     -86.618037       28.       T-10
                              094        N4L05SOI        21-NOV-1998         22:17:18     30.324363     -86.596913       26.       T-10
                              095        N4L04SO2        22-NOV-1998         08:21:15     30.102637     -87.350020       30.       T-10
                              096        N41,04SO4       .22-NOV-1998        10:25:28     29.856763     -87.350582       45.       T-10
                              097        N4LO4SO6        22-NOV-1998         12:18:52     29.656828     -87.350930       79.       T-10
                              099        N4LO4SO9        22-NOV-1998         15:09:47     29.445092     -87.351392       364.      T-7
                              100        N4L04S1I        22-NOV-1998         17:31:44     29.281758     -87.350035       838.      T-7
                              101        N4X03042        22-NOV-1998         20:55:54     29.240618     -87.504847       974.      T-7
                              102        N4XO304I        22-NOV-1998         22:16:39     29.195815     -87.697765       984.      T-7
                              104        N41,03SO6       23-NOV-1998         05:17:00     29.452995     -87.927002       61.       T-10
                              105        N4L03SO4        23-NOV-1998         07:30:59     29.678728     -87.970727       31.       T-10
                              106        N4L03SO2        23-NOV-1998         09:46:18     29.905343     -88.017867       33.       T-10
                              107        N4L02SO2        23-NOV-1998         19:03:28     29.538590     -88.636378       28.       T-10
                              108        N4L02SO4        23-NOV-1998         21:13:07     29.316132     -88.537893       64.       T-10
                              110        N4L02SO7        23-NOV-1998         23:55:12     29.111210     -88.446407       320.      T-7
                              111        N4L02SO9        24-NOV-1998         02:01:43     28.955310     -88.377638       881.      T-7
                              113        N4XO1022        24-NOV-1998         05:18:08     28.798735     -88.555997       1024.     T-7
                              114        N4XOI021        24-NOV-1998         06:38:43     28.741682     -88.758097       989.      T-7
                              116        N4LOIS06        24-NOV-1998         08:59:50     28.701058     -88.911348       922.      T-7
                              117        N4LOIS06        24-NOV-1998         09:12:56     28.730493     -88.923862       775.      T-7
                              118        N4LOIS05        24-NOV-1998         09:28:50     28.766982     -88.935768       628.      T-7
                              119        N4LOIS04        24-NOV-1998         10:31:12     28.808113     -88.946460       491.      T-7
                              120        N4LOIS03        24-NOV-1998         11:57:51     28.923172     -88.986128       146.      T-10
                              121        N4LOIS02        '24-NOV-1998        12:55:53     28.985717     -89.006293       73.       T-10
                              122        N4LOIS02        24-NOV-1998         13:10:21     29.015960     -89.016973       55.       T-10
                              123        N4LOIS01        24-NOV-1998         13:20:59     29.039025     -89.024137       39.       T-10


                       Launches missing sequence numbers were failures, except number 31 was determined bad
                       during QA/QC, and numbers 70 and 90, where there was no launch but the counter advanced.











                                                                                                                31


  A               3.1.3 Cruise N5

                  The fifth NEGOM-COH hydrography cruise (N5) was conducted aboard the RIV Gyre 15-28
                  May 1999. It was staged out of Galveston, TX Dr. Douglas C. Biggs and Dr. Norman L.
                  Guinasso, Jr., were co-chief scientists. One hundred three CTD stations, including the test
                  station, were completed and 118 XBT drops were made. CTD and XBT locations and cruise
                  track are shown in Figure 3,13. Only the locations of the 96 successful XBT drops are shown.
                  A first test station in Mississippi Canyon failed due to an electrical short. A successful test
                  station (000, N5TESTO I) was taken approximately at the seawardmost CTD station on line I
                  and used the back-up CTD system. From this point, the cruise track ran along the 1000-m
                  isobath to the seawardmost CTD station on line 4; XBTs were deployed and ADCP data were
                  recorded during this transit. The first CTD station was taken at the seaward end of line 4, but
                  the CTD package failed at about the 140-m depth. Due to failure of both the main and back-up
                  CTD systems, XBTs were deployed at CTD and XBT stations as the cruise diverted up line 4
                  toward Pensacola, FL. Systems were repaired and CTD station 002 was taken at N5LO4SO5.
                  The cruise then proceeded south, taking the CTD stations on the south half of the line. At the
                  seaward end of line 4, the cruise track again ran along the 1000-m isobath to the seawardmost
                  station on line 11. XBTs were dropped during this transit. CTD stations began again with the
                  seawardmost station of line 11. On the return to line 4, CTDs were taken from the innermost
                  station through and including a repeat of N5LO4SO5 (station number 082). The track then
                  transited to the seawardmost station on line 3 and the normal sampling pattern resumed. The
                  station number, date, time, location, water depth, and number of bottles tripped at each CTD
                  station are shown in Table 3.1.7.


                  Stations at which bottle samples were taken are summarized in Table 3.1.8. Nutrients and
                  oxygen were measured from every Niskin bottle depth sampled. Salinity was measured at all
                  bottles at the most shoreward and most offshore stations, the test station, and at stations with
                  bottle tripping problems, including double bottle trips, for at total of 48 stations. Pigment
                  measurements were collected at the top bottle, the chlorophyll-maximum as determined by the
                  downcast fluorescence trace, and the low light regime immediately below the
                  chlorophyll-maximum at 61 stations. PM, POC, and PON were measured from the top and
                  bottom bottles and, for PM, from a middle, "clear water" bottle at 61 stations. Surface bucket
                  salinity samples were taken at 33 CTD/XBT stations over the inner shelf to better define the
                  freshwater gradients that might be associated with springtime river discharge. These locations
                  are noted in Table 3.1.7 with an asterisk.


                  The location, date, time, total water depth, and probe type of the 96 successful XBT drops are
                  listed in Table 3.1.9. Both the ADCP and thermosalinograph ran continuously along the track
                  from west of the test station to west of the innermost station on line I at cruise end.
                  Flow-through, near-surface temperature, conductivity, and fluorescence were logged every 2
                  minutes. Surface samples were filtered and analyzed for chlorophyll a content to calibrate the
                  flow-tbrough fluorescence at 102 locations.


















                      31*N
                                                                                                                              g
                                                        a  ;21        qqdfa'11@11@3@


                                                      Fensa
                                                                                                                              'R
                                                                                                                             -W

                      30                                                                      04
                                                                                             CO,
                                                                                                                         IN. R
                                                                                                                  'NU
                                            0                                                                M
                                                                                                                       0, 2
                                                                                                                         FF-1,



                                                                                                                       M,
                                                                                                                        'WNWO@@g
                                                                                                                              K'j
                      29*N                             3     5


                                                             6


                                                                7

                      28-N
                                                                            9
                                       * CTDIBottle - 102 Stations
                                                                                10                                         A
                                       * XBT - 96 Stations                                                               -1- 11 I'll, @ -'!,
                                                                                                                       . . . . . . . . . . . .


                                                                                                                    0.    . . . . . . . .


                      27*N
                         901W         89*W        88*W         87*W        86'W         85*W         84*W         83*W        82*W





                    Figure 3.1.3. Station locations for cruise N5 conducted 15 - 28 May 1999. CTD stations began with the most
                                 seaward station on line 4. The thick line shows the cruise track, which began at the location of
                                 the most seaward station on line 1.











                                                                                                                   33

                    Four complementary research efforts, summarized below, were accommodated on cruise N5.
                    Further information on these programs can be obtained from the scientists involved.

                    1) Net tows were made near local noon at 3 locations and at local midnight at 3 locations to
                    collect zooplankton for Rebecca Scott, graduate student of Dr. Biggs, for her thesis research on
                    correlation of standing stocks of zooplankton and micronekton with volume backscatter from
                    upward-looking, moored ADCPs. As on previous cruises N2, N3, and N4, a one-meter net of
                    333-Arn mesh was towed obliquely from surface to 100 ni and back again to the surface.

                    2) A marine mammal distribution and abundance survey was conducted using bigeye binoculars
                    by graduate students Joel Ortega-Ortiz, Trent Apple, and Glenn Gailey, assisted by Maureen
                    Whittaker, an intern/volunteer with the TAMU-Galveston MIVW. This survey continued
                    similar bigeye survey work done on previous cruises N I through N4. Mr. Ortega-Ortiz will use
                    this second springtime cruise of data in his dissertation. During N5, the four observers searched
                    1409 km of transect during 84 hours of effort and made 100 sightings, including sperm whales
                    (7 individuals), Bryde's whale (the first sighting ever from RIV Gyre), and pygmy sperm and
                    dwarf sperm whales.

                    3) Bisman Nababan and David Palandro, graduate students of Dr. Frank Muller- Karger of the
                    USF Remote Sensing Laboratory, made bio-optical measurements of downwelling and
                    sea-leaving radiance. When sunny days pennitted, they used a multichannel Marine
                    Environmental Radiometer twice daily at about 1000- 1100 and 1400-1600 local time. The main
                    objective was to continue and extend bio-optical data collection to calibrate a SeaWiFS satellite
                    receiver and produce an algorithm for chlorophyll concentration estimates in the Gulf ofMexico
                    using SeaWiFS satellite imagery. They also continued and extended the along7track
                    measurement of dissolved organic matter fluorescence that USF had begun on previous cruises
                    N3 and N4, and they sampled for dissolved organic matter from several depths at some of the
                    CTD stations.


                    4) Elise Waltman, undergraduate student at TAMU, lead the effort to collect flow cytometry
                    samples for post-cruise study by Dr. Lisa Campbell, TAMU Oceanography. Dr. Campbell will
                    characterize the vertical distributions of bacteria and picophytoplankton in the northeastern
                    Gulf











                      34

                                       Table 3.1.7. Times and positions for CTD stations on cruise N5.


                          Station       Station           Date          Time       Latitude      Longitude     Depth      No. of
                         Number         Name             (UTC)          (UTC)         (ON)          (OW)         (m)      Bottles
                            000        N5TESTOl      16-AIAY- 1999      18:43:01   28.666397     -88.899783      990.0       12
                            001        N5L04SI2      17-MAY-1999        06:20:00   29.194797     -87.349723     1000.0       0
                            002        N51,04SO5     17-MAY-1999        13:24:49   29.720580     -87.369063        70.0      12*
                            003        N5L04SO7      17-MAY-1999        14:53:51   29.568103     -87.352330      104.0       12*
                            004        N5L04SO8      17-MAY-1999        16:03:52   29.531955     -87.352423      192.0       8
                            005        N5L04SIO      17-MAY-1999        18:06:12   29.371755     -87354657       496.0       12
                            006        N5LO4SI2      17-MAY-1999        20:33:26   29.194047     -87.351255     1006.0       0
                            007        N5L04Sl2R     17-MAY-1999        21:45:29   29.194049     -87,351902     1006.0       12
                            008        N51,11S18     18-MAY-1999        15:56:00   27.498903     -85.394330     1010.0       12
                            009        N51,11S16     18-MAY-1999        18:20:23   27,498122     -85.224645      759*0       12
                            010        N5LIlSl4      18-NlAY-1999       20:25:11   27,500277     -85.074872      496.0       12
                            Oil        N5L]IS12      18-MAY-1999        22:08:06   27.500343     -84.888242      296.0       12
                            012        N5LIlSlO      18-NlAY-1999       23:47:28   27.501000     -84.680917      199.0       12
                            013        N5LllSO8      19-MAY-1999        02:11:34   27.499068     -84.342917        99.0      12
                            014        N5LIlSO6      19-NUY- 1999       04:43:12   27.499638     -83.943517        57.0      7
                            015        N5LllSO4      19-MAY-1999        07:43:35   27.501610     -83.497692        42.0      5
                            016        N5LIlSO2      19-MAY-1999        10:49:21   27.499157     -83.022852        21.0      4
                            017        N51,11SOI     19-MAY-1999        12:04:01   @7.498170     -82.852835        11.0      4
                            018        N5LIOS01      19-MAY-1999        20:04:17   28.606642     -83.056983        11.0      4
                            019        N5LIOS03      19-MAY-1999        22:02:07   28.519330     -83.331008        19.0      6
                            020        N5LIOS05      20-MAY-1999        00:28:15   28.399972     -83.701697        30.0      5
                            021        N5LIOS07      20-MAY-1999        02:53:32   28.285450     -84.059290        38.0      6
                            022        N51,10S09     20-MAY-1999        05:18:03   28.175087     -84.401635        59.0      6
                            023        N5LIOS11      20-MAY-1999        07:35:18   28.076047     -84.708888      104.0       12
                            024        N5LIOS13      20-MAY-1999        09:02:46   28.022160     -84.877715      200.0       12
                            025        N5LIOS15      20-MAY-1999        10:46:14   27.959202     -85.072582      313.0       12
                            026        N5LIOS17      20-MAY-1999        12:33:27   2T894930      -85.276928      494.0       12
                            027        N5LIOS19      20-NUY-1999        14:14:34   27.848422     -85,410365      654.0       11
                            028        N5LIOS21      20-MAY-1999        16:41:19   27.782290     -85,628507      991.0       12
                            029        N5LO9S21      20-MAY-1999        21:12:03   28.019585     -86.043080      975.0       12
                            030        N5L09SI9      20-MAY-1999        23:22:22   28.117013     -85.879123      675.0       12
                            031        N51,09SI7     21-MAY-1999        01:00:31   28.190275     -85.753612      502.0       12
                            032        N5L09SI5      21-MAY-1999        03:05:45   28.308977     -85.560913      304.0       12
                            033        N51,09S 13    21-MAY-1999        04:45:04   28.411577     -85.396290      199.0       12
                            034        N5L09SlI      21-MAY-1999        06:20:05   28.507863     -85.236182      162.0       12
                            035        N5LO9SO9      21-MAY-1999        08:26:28   28.626692     -85.044860        97.0      12
                            036        N51,09SO7     2 1 -NMY- 1999     11:20:18   28.839577     -84.694638        45.0      6*
                            037        N5LO9SO5      21-MAY-1999        14:46:23   29.105920     -84.256193        26.0      6*
                            038        N5LO9SO3      21-MAY-1999        18:00:21   29.342285     -83.861790        19.0      4*
                            039        N51,09SOI     21-MAY-1999        20:21:01   29.517190     -83.583545          9.0     4 *
                            040        N5LO8SOI      22-MAY-1999        03:23:26   29.611940     -84.783363        10.0      3*
                            041        N51,08SO3     22-MAY-1999        05:54:40   29.369840     -85.036547        26@O      4*
                            042        N51,08SO5     22-AMY-1999        08:01:31   29.203835     -85.274507        41.0      8 *
                            043        N51,08SO7     22-MAY-1999        10:17:48   28.984423     -85.527525      132.0       12
                            044        N51,08SO9     22-MAY-1999        12:10:49   28.824273     -85.717948      197.0       12
                            045        N5LO8SIl      22-MAY-1999        15:16:48   28.605673     -85.975782      308.0       12











                                                                                                                                        35

                                  Table 3.1.7. Times and positions for CTD stations on cruise N5 (continued).


                            Station       Station            Date           Time       Latitude      Longitude       Depth      No. of
                           Number          Name             (UTC)           (UTC)         (ON)          (OW)          (m)      Bottles
                              046       N5LO8SI3        22-MAY-1999         17:50:05   28A01888      -86.216608       498.0       12
                              047       N5L08SI5        22-MAY-1999         19:45:18   28.296818     -86.337912       672.0       12
                              048       N5LO8SI7        22-MAY- 1999        22:05:39   28.132987     -86.533230       997.0       12
                              049       N51,07SI7       23-MAY-1999         01:55:38   28.371348     -86.988037      1005.0       12
                              050       N5L07SI5        23-MAY-1999         04:35:29   28.558022     -86.77381-7      666.0       12
                              051       N5LO7SI3        23-MAY-1999         06:41:02   28.700983     -86.612193       498.0       12
                              052       N51,07SII       23-MAY-1999         08:56:32   28.862460     -86,424810       381.0       12
                              053       N5LO7SO9        23-MAY-1999         10:59:51   29.016905     -86.245912       315.0       12
                              054       N5LO7SO7        23-MAY-1999         13:16:04   29.207792     -86.028670       200.0       12
                              055       N51,07SO5       23-NlAY-1999        14:38:52   29.298867     -85.921888         94.0      12
                              056       N5L07SO3        23-MAY-1999         17:03:58   29.500120     -85.693242         30.0      5 *
                              057       N5L07SOl        23-MAY-1ï¿½99         19:09:35   29.687695     -85.480335         20.0      4k
                              058       N5LO7SOO        23-MAY-1999         20:03:05   29.736615     -85.424360         10.0      3*
                              059       N5LO6SOI        24-MAY-1999         00:17:58   30.179210     -85.884550         20.0      4*
                              060       N5L06SO3        24-MAY-1999         01:54:43   30.018400     -86.022882         31.0      4*
                              061       N5L06SO5        24-MAY-1999         03:j5:49   29.852383     -86.165463         46.0      4*
                              062       N5LO6SO7        24-MAY-1999         05:24:49   29.686750     -86.306370         97.0      12
                              .063      N5LO6SO9        24-MAY-1999         08:16:08   29.499780     -86.471173       202.0       12
                              064       N5L06SII        24-MAY-1999         10:23:05   29.314053     -86.629422       380.0       12
                              065       N51,06S 13      24-MAY-1999         12:29:50   29.132555     46.787305        498.0       12
                              066       N5LO6SI5        24-MAY-1999         14:25:25   28.981422     -86.918503       615.0       12
                              067       N5LO6SI7        24-MAY-1999         16:27:16   28.826552     -87.052647       767.0       12
                              068       N5LO6SI9        24-MAY-1999         18:49:16   28.652740     -87.202405       994.0       12
                              069       N5LO5SI7        24-MAY-1999         22:33:41   29.054807     -87.206902      1001.0       12
                              070       N5LO5SI5        25-MAY-1999         01:15:57   29.273477     -87.104998       710.0       0
                              071      N5LO5Sl5R        25-MAY-1999         01:37:57   29.268447     -87.101625       710.0       11
                              072       N51,05SI3       25-MY-1999          03:37:26   29.468453     -87.010285       489.0       12
                              073       N5LO5SII        25-MAY-1999         05:26:05   29.608445     -86.939208       261.0       12
                              074       N51,05SO9       25-MAY-1999         06:47:25   29.723748     -86.884882       198.0       12
                              075       N5LO5SO7        25-MAY-1999         08:28:52   29.880072     -86.809135       147.0       12
                              076       N5L05SO5        25-MAY-1999         10:08:18,  30.027400     -86.735810         98.0      12
                              077       N5LO5SO3        25-MAY-1999         11:45:57   30.202378     -86.655312         36.0      5*
                              078       N5LO5SOI        25-MAY-1999         13:10:56   30.367033     -86.578658         16.0      4*
                              079       N5L04SOO        25-MAY-1999         18:20:52   30.290792     -87.348292           8.0     3 *
                              080       N51,04SOI       25-MAY-1999         19:10:10   30.221707     -87351263          18.0      4*
                              081       N5LO4SO3        25-MAY-1999         21:05:52   29.979695     -87.350470         28.0      5**
                              082      N5L04SO5R        25-MAY-1999         22:56:54   29.728768     -87.349355         79,0      8
                              083       N5LO3SIO        26-NIAY-1999        04:23:55   29.151557     -87.860423      1019.0       12
                              084       N51,03SO9       26-MAY-1999         05:59:08   29.219167     -87.874867       455.0       12*
                              085       N5L03SO8        26-MAY-1999         07:06:38   29.283477     -87.888047       200.0       12*
                              086       N5LO3SO7        26-MAY-1999         08:05:54   29.347317     -87.901742         94.0      12
                              087       N5LO3SO5        26-NUY- 1999        09:57:27   29.556323     -87.947060         40.0      6*
                              088       N51,03SO3       26-MAY-1999         11:55:43   29.801343     -87.996628         37.0      5 *
                              089       N5LO3SOI        26-MAY-1999         14:20:14   30.099568     -88.071337         20.0      4*
                              090       N5LO3SOO        26-MAY-1999         15:03:22   30.156123     -88.090488         12.0      4 *
                              091       N51,02SOO       26-MAY-1999         20:12:53   29.799803     -88.753942         14.0      4*











                      36

                                Table 3.1.7. Times and positions for CTD stations on cruise N5 (continued).


                          Station        Station            Date          Time        Latitude    Longitude        Depth    No. of
                          Number         Name               (UTC)         (UTC)         (ON)         (OW)          (m)      Bottles
                             092         N5LO2SOI     26-MAY-1999         21:25:48    29.664712   -88.694368         18.0         6*
                             093         N5LO2SO3     26-MAY-1999         23:33:45    29.394088   -88.570398         58.0         6
                             094         N5LO2SO5     27-MAY-1999         00:57:19    29.223547   -88.496293       113.0          12
                             095         N51,02SO6    27-MAY-1999         02:04:37    29.173192   -88.472357       191.0          12
                             096         N5LO2SO8     27-MAY-1999         03:18:49    29.046382   -88.415820       506.0          12
                             097         N51,02SIO    27-MAY-1999         05:12:54    28.867828   -88.337708       996.0          12
                             098         N51,01S07    27-MAY-1999         09:46:46    28.660740   -88.898337       1014.0         12*
                             099         N5LOIS05     27-NlAY-1999        12:01:30    28.804893   -88.947510       501.0          12*
                             100         N51,01S04    27-NlAY-1999        13:22:56    28.895500   -88.974608       205.0          12*
                             101         N51,01S03    27-MAY-1999         14:36:58    28.956793   -88.995408       101.0          12
                             102         N5LOIS01     27-NIAY-1999        15:44:04    29.059717   -89.030182         17.0         5*
                          Additionally a surface bucket salinity sample was drawn here.
                          A surface bucket salinity sample was drawn here and also at a light meter cast just before
                          this station.




                                         Table 3.1.8 Number of bottles sampled by variable on cruise N5.

                          Station        Station      Nutrients      Oxygen       Salinity     Pigments        PM*         POC &
                          Number         Name                                                                               PON*
                             000         N5TEST01           12            12          12            0              0              0
                             001         N51,04SI2          0             0           0             0              0              0
                             002         N5LO4SO5           12            12          12            3              3              2
                             003         N5LO4SO7           12            12          0             3              3              2
                             004         N5L04SO8           8             8           8             3              1              1
                             005         N5LO4SIO           12            12          2             3              3              2
                             006         N51,04SI2          0             0           0             0              0              0
                             007         N5LO4Sl2R          12            12          12            3              2              1
                             008         N5LllSI8           12            12          12            5              3              2
                             .009        N5LIlSI6           12            12          2             0              0              0
                             010         N51,11S14          12            12          2             3              3              2
                             Oil         N5LIISl2           12            12          2             0              0              0
                             012         N5LIISI0           12            12          3             3              3              2
                             013         N5L1IS08           12            12          2             3              3              2
                             014         N5LIIS06           7             7           0             0              0              0
                             015         N51,11S04          5             5           0             3              3              2
                             016         N5LIlSO2           4             4           0             2              2              2
                             017         N5LllS0I           4             4           4             0              0              0
                             018         N5LIOS01           4             4           4             0              0              0
                             019         N5LIOS03           6             6           0             2              3              2
                             020         N5LIOS05           5             5           0             2              3              2
                             021         N5LIOS07           6             6           0             2              3              2
                             022         N51,10S09          6             6           0             0              0              0
                             023         N5LIOS11           12            12          12            3              3              2











                                                                                                               37

                           Table 3.1.8 Number of bottles sampled by variable on cruise N5 (continued).

                      Station     Station    Nutrients    Oxygen     Salinity  Pigments      PM*       POC &
                      Number       Name                                                                PQN*
                        024      N5L10S13        12          12         12          3          3          2
                        025      N51,10S15       12          12         12          0          0          0
                        026      N5LIOS17        12          12         0           4          3          2
                        027      N5LIOS19        I I         I 1        0           0          0          0
                        028      N5L10S21        12          12         12          3          3          2
                        029      N5LO9S21        12          12         12          3          3          2
                        030      N5L09SI9        12          12         0           0          0          0
                        031      N5LO9SI7        12          12         0           3          3          2
                        032      N5L09SI5        12          12         0           0          0          0
                        033      N5LO9SI3        12          12         12          3          3          2
                        034      N5L09SII        12          12         0           0          0          0
                        035      N5LO9SO9        12          12         0           4          3          2
                        036      N51,09SO7       6           6          0           3          3          2
                        037      N5LO9SO5        6           6          0           2          3          2
                        038      N5L09SO3        4           4          0           2          3          2
                        039      N5LO9SOI        4           4          4           0          0          0
                        040      N51,08SOI       3           3          3           0          0          0
                        041      N5LO8SO3        4           4          0           2          3          2
                        042      N5LO8SO5        8           8          8           0          0          0
                        043      N5L08SO7        12          12         12          4          3          2
                        044      N51,08SO9       12          12         0           3          3          2
                        045      N51,08SII       12          12         12          0          0          0
                        046      N5L08SI3        12          12         2           3          3          2
                        047      N5L08SI5        12          12         2           0          0          0
                        048      N5LO8SI7        12          12         12          3          3          2
                        049      N5LO7SI7        12          12         12          3          3          2
                        050      N5LO7SI5        12          12         0           0          0          0
                        051      N5LO7SI3        12          12         0           4          3          2
                        052      N5L07SII        12          12         0           0          0          0
                        053      N5LO7SO9        12          12         12          0          0          0
                        054      N5LO7SO7        12          12         0           4          3          2
                        055      N51,07SO5       12          12         0           3          3          2
                        056      N5LO7SO3        5           5          2           0          0          0
                        057      N5LO7SOI        4           4          0           2          3          2
                        058      N51,07SOO       3           3          3           0          0          0
                        059      N5LO6SO1        4           4          4           2          3          2
                        060      N5LO6SO3        4           4          0           0          0          0
                        061      N5LO6SO5        4           4          0           0          0          0
                        062      N51,06SO7       12          12         12          4          3          2
                        063      N5LO6SO9        12          12         0           3          3          2
                        064      N5L06SII        12          12         0           0          0          0
                        065      N51,06SI3       12          12         12          4          3          2
                        066      N5L06SI5        12          12         0           0          0          0
                        067      N5L06SI7        12          12         0           0          0          0
                        068      N51,06SI9       12          12         12          3          3          2
                        069      N51,05SI7       12          12         12          3          3          2











                   38

                           Table 3.1.8 Number of bottles sampled by variable on cruise N5 (continued).

                      Station     Station     Nutrients   Oxygen     Salinity   Pigments      PM*       POC &
                     Number        Name                                                                  PON*
                        070      N51,05SI5         0           0         0          0           0          0
                        071     N5L05S15R          I I         I I       I 1        0           0          0
                        072      N5LO5SI3          12          12        0          3           3          2
                        073      N5L05SII          12          12        0          0           0          0
                        074      N5LO5SO9          12          12        5          5           3          2
                        075      N5LO5SO7          12          12        12         0           0          0
                        076      N5LO5SO5          12          12        0          3           3          2
                        077      N5L05SO3          5           5         0          0           0          0
                        078      N5LO5SOI          4           4         0          2           3          2
                        079      N5LO4SOO          3           3         3          0           0          0
                        080      N5L04SOI          4           4         0          2           3          2
                        081      N5LO4SO3          5           5         2          0           0          0
                        082     N5LO4SO5R          8           8         0          0           0          0
                        083      N5LO3SIO          12          12        12         3           3          2
                        084      N5L03SO9          12          12        0          3           3          2
                        085      N5LO3SO8          12          12        0          3           3          2
                        086      N51,03S07         12          12        0          4           3          2
                        087      N5LO3SO5          6           6         0          0           0          0
                        088      N51,03SO3         5           5         0          0           0          0
                        089      N5L03SOI          4           4         0          2           3          2
                        090      N5LO3SOO          4           4         4          0           0          0
                        091      N5LO2SOO          4           4         4          0           0          0
                        092      N5LO2SOI          6           6         0          3           3          2
                        093      N51,02SO3         6           6         0          0           0          0
                        094      N5LO2SO5          12          12        0          2           3          2
                        095      N5LO2SO6          12          12        0          2           3          2
                        096      N5LO2SO8          12          12        0          3           3          2
                        097      N5L02SIO          12          12        12         4           3          2
                        098      N5LOIS07          12          12        12         4           3          2
                        099      N5LOIS05          12          12        0          3           3          2
                        100      N5LOIS04          12          12        0          3           3          2
                        101      N5LOIS03          12          112       3          3           3          2
                        102      N5LOIS01          5           5         5          3           3          2
                     POC = particulate organic carbon; PON       particulate organic nitrogen; PM    total particu-
                    late material; R = Repeat of station cast











                                                                                                                                  39

                                     Table 3.1.9 Launch times and locations for XBT drops on cruise N5.


                          Sequence        Station           Date          Time       Latitude      Longitude     Water      Probe
                          Number*          Name            (UTC)          (UTC)         (ON)         (OW)        Depth      Type
                                                                                                                  (M)   '
                              001        N5XO102M       16-NlAY-1999      21:58:12   28.749868     -88.599668     990,0      T7
                              002        N5L02S10       16-MAY-1999       23:46:51   28.869473     -88.337737     996.0      T7
                              003        NSX0203M       17-MAY-1999       01:34:17   29.039445     -88.109035    1000.0      T7
                              004        N51,03SIO      17-MAY-1999       03:16:22   29.151522     -87.860842    1019.0      T7
                              007        N5X0304M       17-MAY-1999       04:41:43   29.202892     -87.619437     980.0      T7
                              008        N5L04Sl2       17-MAY-1999       07:35:10   29.199160     -87.344155    1006.0      T7
                              009        N5L04Sll       17-NIAY-1999      08:24:32   29.282365     -87.350738     838.0      T7
                              Oil        N5L04Sl0       17-MAY-1999       09:14:18   29.375908     -87.350723     481.0      T7
                              012        N5LO4SO9       17-MAY-1999       09:53:00   29.450082     -87.351700     356.0      T7
                              013        N5L04SO8       17-MAY-1999       10:35:06   29.532043     -87.351208     178.0      TIO
                              014        N5LO4SO7       17-MAY-1999       10:54:23   29.568020     -87.350762     107.0      TIO
                              015        N51,04SO6      17-MAY-1999       11:40:45   29.657083     -87.350683       80.0     TIO
                              016        N51,05SI7      17-MAY-1999       23:56:18   29.054750     -87.205100     493.0      T7
                              017        NSX0506M       18-MAY-1999       01:11:49   28.869243     -87.199128     998.0      T7
                              018        N5LO6SI9       18-MAY-1999       02:38:28   28.653043     -87.202357     994.0      T7
                              020        NSX0607M       18-MAY-1999       03:50:32   28.482500     -87.118520     967.0      T7
                              021        N51,07SI7      18-MAY-1999       04:52:43   28.370910     -86.988190    1035.0      T7
                              022        N5XO708M       18-MAY-1999       06:42:50   28.261122     -86.759127    1123.0      T7
                              024        N51,08SI7      18-MAY-1999       08:20:02   28.129373     -86' 526427   1230.0      T7
                              025        N5XO809M       18-MAY-1999       09:39:14   28.057558     -86.303443    1006.0      T7
                              026        N5L09S2l       18-MAY-1999       11:05:14   28.018955     -86.042813     975.0      T7
                              028        N5X09l0M       18-MAY-1999       12:29:48   27.895843     -85.809000     992.0      T7
                              029        N5LIOS21       18-MAY-1999       13:38:34   27.783690     -85@630532     981.0      T7
                              031        N5XIO11M       18-MAY-1999       14:43:38   27.641718     -85.502062    1156.0      T7
                              032        MMIS17         18-MAY-1999       17:47:37   27.500140     -85.294072     835.0      T7
                              035        N51,11S15      18-MAY-1999       20:02:10   27.503528     -85.123215     633.0      T7
                              036        N5LIlSl3       18-MAY-1999       21:33:03   27.500512     -84.977695     390.0      T7
                              037        N5LllSll       18-MAY-1999       23:05:28   27.500395     -84.791913     235.0      T7
                              038        N51,11S09      19-MAY-1999       01:03:43   27.500220     -84.523787     138.0      TIO
                              039        N51,11S07      19-MAY-1999       03:29:02   27.500093     -84.159768       70.0     TIO
                              040        N5Ll:lSO5      19-MAY-1999       06:10:30   27.500850     -83.732597       49.0     TIO
                              041        N5LllS03       19-MAY-1999       09:21:40   27.499918     -83.149893       33.0     T10
                              042        N51,10S02      19-MAY-1999       21:06:27   28.563855     -83.195073       17.0     T10
                              043        N5L10S04       19-MAY-1999       23:22:14   28.456048     -83.528295       26.0     T10
                              044        N5LIOS06       20-MAY-1999       01:44:21   28.340145     -83.887077       28.0     TIO
                              045        N51,10SO8      20-MAY-1999       04:08:13   28.223740     -84.239738       49.0     TIO
                              046        N5LIOSIO       20-MAY-1999       06:35:27   28.122425     -84.569272       74.0     TIO
                              047        N51-10S12      20-MAY-1999       08:28:12   28.048683     -84.799102     150.0      TIO
                              049        N51,10S14      20-MAY-1999       10:06:22   27.990628     -84.981053     250.0      T7
                              050        N5LIOS16       20-NlAY-1999      11:46:12   27.930612     -85.167028     391.0      T7
                              053        N5L10Sl8       20-MAY-1999       13:33:26   27.874315     -85.344273     594.0      T7
                              055        N51,10S20      20-MAY-1999       15:50:57   27.817552     -85.525715     751.0      T7
                              056        N5LO9S20       20-MAY- 1999      22:48:12   28.072080-    -85.950800     804.0      T7
                              059        N5L09Sl8       21 -NUY- 1999     00:32:37   28.158722     -85.806980     588.0      T7
                              063        N5L09Sl6       21-MAY-1999       02:27:14   28.261105     -85.638998     359.0      T7











                     40

                             Table 3.1.9 Launch times and locations for XBT drops on cruise N5 (continued).


                         Sequence        Station           Date           Time       Latitude     Longitude      Water      Probe
                         Number*          Name            (UTC)           (UTC)        (ON)          (OW)        Depth      Type
                                                                                                                  (M)
                             065        N5LO9SI4       21-NIAY-1999       04:07:04   28.362018    -85.475690      240.0     T7
                             066        N5L09S12       21-MAY-1999        05:39:53   28.457683    -85.318842      179.0     TIO
                             067        N5L09SIO       21-MAY-1999        07:30:28   28.567287    -85.138983      129.0     TIO
                             068        N51,09SO8      21-MAY-1999        09:54:32   28.723962    -84.881827       51.0     TIO
                             069        N5LO9SO6       21-MAY-1999        13:04:07   28.971828    -84.475917       35.0     TIO
                             070        N5L09SO4       21-MAY-1999        16:20:07   29.230437    -84.051945       25.0     TIO
                             071        N5LO9SO2       21-MAY-1999        19:10:24   29.427340    -83.728713       16.0     TIO
                             072        N5LO8SO2       22-MAY-1999        04:18:16   29.533313    -84.887210       14.0     TIO
                             074        N51,08SO4      22-MAY-1999        06:40:25   29.325828    -85.132370       27.0     TIO
                             075        N51,08SO6      22-MAY-1999        09:15:11   29.094267    -85.403170       50.0     T10
                             077        MUMS           22-NIAY-1999       11:23:07   28.902332    -95.627907      171.0     TIO
                             078        N5LO8SIO       22-MAY-1999        13:40:00   28.709927    -85.854018      261.0     T7
                             079        N5L08S12       22-NUY- 1999       16:54:04   28.496633    -86.104488      379.0     T7
                             080        N5LO8SI4       22-MAY-1999        19:14:04   28,341605    -86.287378      581.0     T7
                             081        N5LO8SI6       22-MAY-1999        21:16:43   28.213132    -86.438453      819.0     T7
                             083        N51,07SI6      23-MAY-1999        03:43:10   28.466572    -86.878578      778.0     T7
                             085        N5L07SI4       23-MAY-1999        06:02:46   28.638803    -86.680362      579.0     T7
                             086        N5L07S12       23-NfAY-1999       08:05:07   28.784448    -86.513962      424.0     T7
                             087        N51,07S10      23-M&Y-1999        10:13:00   28.944987    -86.329962      344.0     T7
                             088        N5LO7SO8       23-MAY-1999        12:23:06   29.119720    -86.127405      257.0     T7
                             089        N51,07SO6      23-NlAY-1999       14:04:53   29.251542    -85.978907      158.0     TIO
                             090        N5L07SO4       23-MAY-1999        15:57:19   29.387597    -85.822815       51.0     TIO
                             091        N51,07SO2      23-MAY-1999        18:15:31   29.593750    -85.586787       28.0     TIO
                             092        N51,06SO2      24-NlAY-1999       01:07:51   30.098877    -85.954773       30.0     T10
                             093        N5L06SO4       24-MAY-1999        02:44:16   29.942408    -86.090025       40.0     TIO
                             094        N5L06SO6       24-MAY-1999        04:38:19   29.759083    -86.248243       68.0     TIO
                             095        N51,06SO8      24-MAY-1999        06:27:17   29.600320    -86.384948      129.0     T10
                             096        N5L06SIO       24-MAY-1999        09:26:10   29.410417    -86.548977      285.0     TIO
                             097        N5L06SI2       24-MAY-1999        11:37:00   29.225933    -86.708037      433.0     T7
                             098        N51,06SI4      24-MAY-1999        13:45:18   29.048705    -86.860882      502.0     T7
                             099        N5LO6SI6       24-MAY-1999        15:38:02   28.911840    -86.979082      664.0     T7
                             100        N51,06SI8      24-MAY-1999        17:58:29   28.742610    -87,124932      838.0     T7
                             101,       N51,05SI6      25-MAY-1999        00:29:48   29.181297    -87.150042      825.0     T7
                             102        N5LOSS14       25-MAY-1999        02:52:34   29,374718    -87.055578      623.0     T7
                             103        N5L05S12       25-NlAY-1999       04:41:09   29.533930    -86.979005      342.0     T7
                             104        N5L05SIO       25-MAY-1999        06:17:08   29.671210    -86.912920      220.0     TIO
                             105        N51,05SO8      25-NlAY-1999       07:47:41   29M8157      -86.847023      169.0     TIO
                             106        N51,05SO6      25-MAY-1999        09:25:10   29.959593    -86.773817      124.0     TIO
                             107        N5LO5SO4       25-MAY-1999        11:01:05   30.111158    -86.700718       95.0     TIO
                             108        N5L05SO2       25-MAY-1999        12:31:21   30.283422    -86.617528       28.0     TIO
                             109        N5LO4SO2       25-MAY-1999        20:05:28   30.102883    -87.351005       30.0     TIO
                             110        N5L04SO4       25-MAY-1999        22:03:13   29.856622    -87.353187       44.0     TIO
                             III        N5LO3SO6       26-MAY-1999        09:09:06   29.452913    -87.928075       62.0     TIO
                             112        N5LO3SO4       26-NIAY-1999       11:00:46   29.678142    -87.972053       41.0     TIO
                             113        N5LO3SO2       26-MAY-1999        13:09:43   29.95321.3   -88.038470       33.0     TIO











                                                                                                                              41

                             Table 3.1.9 Launch times and locations for XBT drops on cruise N5 (continued).


                          Sequence       Station          Date          Time      Latitude     Longitude      Water   Probe
                          Number*         Name            (UTQ         (UTQ          (ON)         (OW)        Depth    Type
                                                                                                              (m)  '
                             114        N5L02SO2      2&MAY-1999       22:27:05   29.538692    -88.634897       29.0    TIO
                             115        N5LO2SO4      27-MAY- 1999     00:15:54   29.316062    -88.537555       65.0    TIO
                             116        N5LO2SO7      27-MAY-1999      02:42:53   29.122967    -88.450927     289.0     T7
                             117        N5L02SO9      27-MAY-1999      04:27:26   28.955068    -88.376638     881.0     T7
                             119        N5LOIS06      27-MAY-1999      11:25:50   28.736552    -88.925840     754.0     T7
                             120        N5LOIS02      27-MAY-1999      15:22:07   29.015678    -89.017038       55.0    TIO
                        Launches of 21 T7s and I T 10 failed due to bad probes; missing sequence numbers 006
                        and 076 were cases where there was no launch but the counter advanced.




                       3.2 Instrumentation, Calibration, and Sampling Procedures

                       Standard oceanographic instrumentation and sampling procedures were used to collect
                       measurements on the NEGOM-COH cruises. Data taken at each station consist of five
                       types-continuous profiles, discrete measurements, ADCP measurements, XBT profiles, and
                       supplementary underway measurements. The equipment and data collection procedures for
                       each were summarized in the first NEGOM-COH report (Jochens and Nowlin, 1998). Below
                       are given changes in methods or procedures and additional information on data collection.
                       Processing of data from cruises N3 and N4 was completed, but data processing for cruise N5
                       was in progress at the time of this report.

                       3.2.1       Continuous Profiles


                       Continuous profiles versus pressure were made of temperature, conductivity, downwelling
                       irradiance (with a photosynthetically available radiation (PAR) sensor), transmissivity,
                       fluorometry, optical backscatter, and, although not contractually required, dissolved oxygen.
                       Instruments were mounted on the Rosette frame below the Niskin water bottles and Rosette
                       system to provide unperturbed, obstruction-free flow of water to all instruments during the
                       downcast. The various instruments were interfaced with the CTD, which transmitted data to the
                       Sea-Bird SBE- 11 deck unit for data logging and storage. The altimeter allowed the CTD
                       package to be lowered to within 1-5 meters of the sea floor. The hydrographic equipment used
                       on the cruises is given in Table 3.2. 1. Sensor specifications and methods were detailed in
                       Jochens and Nowlin (1998).

                       Two sets of instruments were taken on each cruise to provide back-up instrumentation. This
                       redundancy helped assure collection of complete data sets for each parameter. No major CTD
                       equipment failure occurred on cruises N3 and N4. Major equipment failure on N5 included
                       .problems with the CTD electrical systems and bottle tripping mechanical systems. These











                    42

                    failures were repaired during the cruise. The major impact on data collection was the loss of
                    the deep half (deeper than -4  '00 m) of the CTD cast at N51,05 S 15 (two casts: 70 and 7 1) and the
                    loss of the near-surface water samples at 12 of the 18 stations at which double bottle trips or
                    failure of the Rosette sampler occurred.



                             Table 3.2.1 Hydrographic equipment available on cruises N3, N4, and N5.

                                Instrument                            Manufacturer                        Quantit
                                                                                                              Y
                         CTD system                   Sea-Bird SBE-91 Iplus                                   2
                         CTD deck unit                Sea-Bird SBE- 11                                        2
                         Rosette system               General Oceanics 12 place                               2
                         Rosette frame                TAMU fabrication                                        2
                         Niskin bottles               GO Lever Action, 10 liter                               14
                         Oxygen sensor                Sea-Bird SBE 13, Beckman polarographic                  2
                         Niskin bottles               GO Standard, 10-12 liter                                10
                         Transmissometer              25-cm SeaTech 2000 m                                    2
                         Fluorometer                  Chelsea Instruments                                     2
                         Optical backscatter          SeaTech Light scattering sensor                         2
                         PAR sensor                   Biospherical QSP-200L                                   2
                         Altimeter                    Datasonics PSA-900                                      2






                    3.2.2       Discrete Measurements


                    Water samples for discrete measurements were collected from 1 0-liter Niskin bottles mounted
                    on a General Oceanics Rosette sampler. Typically, four to l2bottles per station were used.
                    Bottles were tripped at the maximum CID depth, at the sea surface (-3 m), and in the
                    chlorophyll maximum as determined from the fluorescence profile by the CTD operator. Other
                    bottles were tripped at the specified sigma-theta surfaces, when present, given in Table 3.2.2.
                    A number of these surfaces are associated with specific water masses in the Loop Current. The
                    CTD operator had the discretion to trip unused bottles to fill gaps in bottle spacing or to sample
                    in interesting features in the temperature, salinity, fluorescence, or percent transmission profiles.
                    On cruise N5, extra bottles, when available, were taken at 20-m and 50-m depths for flow
                    cytometry sampling. Generally, in water depths of 100 m or more, all 12 bottles were tripped
                    regardless of availability of sigma-theta surfaces.

                    Discrete water samples were taken for nutrients (phosphate, silicate, nitrate, nitrite, ammonium,
                    and urea) and dissolved oxygen at all stations and for PK POC/PON, and phytoplankton











                                                                                                                    43

                    pigments at approximately 60 stations. The PM/POC/PON and pigment samples were taken
                    from the same stations to facilitate integration and interpretation of data. For salinity, samples
                    were measured at bottles from the inshore-most and offshore-most stations, from leaking bottles,
                    and for stations with unplanned bottle trips. See Tables 3.1.2, 3.1.5, and 3.1.8 for N3, N4, and
                    N5, respectively, for details.




                                                 Table 3.2.2 Bottle tripping locations.

                                Trip Location                                   Comments
                         Top                                                          generally about 3-m depth
                         Chlorophyll maximum                  as indicated by downcast fluorescence maximum
                         Bottom                                              generally 1 to 5 m above sea floor
                         Available (Y surfaces:
                            24.6
                            25.4                                  salinity maximum in Subtropical Underwater
                            25.9
                            26.2
                            26.5                                oxygen maximum in 18'C Sargasso Sea Water
                            26.8
                            27.0
                            27.15 or 27. 10               oxygen minimum in Tropical Atlantic Central Water
                            27.45                           salinity minimum in Antarctic Intermediate Water
                         Other bottles if available     interesting features in downcast profiles or for spacing




                    Water samples were drawn and processed as soon as the CTD-Rosette system was brought
                    on-board. Analyses of dissolved oxygen, nutrients, and salinity were performed at sea. Samples
                    for PM, POC/PON, and phytoplankton pigments were filtered at sea, and the filters returned for
                    final processing onshore. Methods and analysis specifications were provided in the first
                    NEGOM-COH annual report (Jochens and Nowlin, 1998).

                    Particulate organic nitrogen (PON) measurements were made on all NEGOM-COH cruises.
                    Although not required by the contract, PON data are included in the master bottle data sets for
                    each cruise. Methods of sample collection and analysis for the POOPON filters are described
                    in Jochens and Nowlin (1998). PON and POC values were determined from the same filter
                    sample with a CHN elemental analyzer. The analysis procedure is outlined in the U. S. JGOFS
                    BATS Method Manual (Knap et al., 1997). POOPON filter samples for N1 through N4 were
                    analyzed at the Bermuda Station for Biological Research; filters from N5 were sent for analysis
                    to the Virginia Institute of Marine Science.











                   44

                   3.2.3      Acoustic Doppler Current Profiler Measurements

                   ADCP measurements were made along track on cruises N3, N4, and N5. Data were collected
                   using a 150-kHz broad-band ADCP (SIN 1183) for cruises N3 and N5 and a 150-kHz
                   narrow-band ADCP (S/N 355) for cruise N4. The narrow-band ADCP used on N4 was the
                   back-up to the broad-band ADCP, which had failed early in the cruise when the ship@s bull
                   grazed an uncharted sand bar created by Hurricane Georges, damaging the broad-band ADCP.
                   The assistance of divers was required to remove the damaged ADCP from the instrument well.
                   This occurred at an inshore location on line 4, after which the narrow-band ADCP was
                   operational. Figure 3.2.1 shows the locations of the bins with good data, giving the general
                   cruise tracks for collection of ADCP data. Dates of data collection and quantity of raw ADCP
                   and navigation data are summarized in Table 3.2.3.

                   Both ADCPs were manufactured by RD Instruments, Inc. (RDI). Differential global positioning
                   system (DGPS) fixes were used when available. ADCP data processing, recording, and
                   instrument control used the RDI TRANSECT program. Details on instrument specifications,
                   mounting on the vessel, data processing, and associated navigation data are provided in Jochens
                   and Nowlin (1998).

                   An Ashtech ADU2 3DF positioning antenna array (SIN AD0025 1) was installed on the top deck
                   of the RIV Gyre prior to cruise N3. It was used on cruises N3 through N5 to collect
                   high-precision positioning information. The Ashtech data allowed the processing and quality
                   control of ADCP data collected while on-station. They also allowed the elimination of bad
                   ensembles (lasting 8 to 10 seconds) prior to calculating the 5-minute average segments (see
                   Section 4.4).

                   The configurations recorded for the ADCP during each cruise are shown in Table 3.2.4.
                   Configurations are basically identical for each cruise (except for the use of a narrow-band
                   ADCP during N4) to enhance continuity among the different cruises and to simplify analysis and
                   interpretation.



                                           Table 3.2.3. Dates and quantity of ADCP data


                       Cruise       ADCP Start             ADCP Stop          Acquisition      Quantity of
                                       (UTC)                  (UTC)             Program       Data (Mbyte)
                         N3      25 Jul 1998 04:49 08 Aug 1998 16: 10         TRANSECT              350
                         N4      22 Nov 1998 03:25 24 Nov 1998 23:56          TRANSECT              41
                         N5      15 May 1999 07:45 28 May 1999 02:29          TRANSECT             250










                                                                                                     45



                                  31 *N                             AWN
                                          Siss,           '-paph

                                                                                 51-
                                  30*N



                                  29'N



                                  28*N

                                          Cruise N3

                                  27*N
                                     90*W  89*W  88*W  87*W 86*W     85   84*W 83*W    82*W


                                  31*N
                                                                 P.,
                                                                          C@    'M
                                                                           ggla - I
                                         I Isgp, IR


                                  30*N



                                  29*N



                                  28*N

                                          Cruise N4

                                  27*N
                                     90*W  89*W  88*W 87*W 86*W     85 %k 84*W 83*W    82*W


                                  31*N
                                         -LIU
                                         ,@- , A ''MR,                N
                                           3S iss
                                                          T-Tonda-,


                                  30*N



                                  29*N


                                                                                     M zi
                                  28*N

                                          Cruise N5

                                  27*N
                                     90*W 89*W 88*W 87*W 8 *w 85          84*W 83*W    82*W



                      Figure 3.2. 1. Locations of ensemble ADCP data for cruises N3, N4, and N5.











                   46

                                             Table 3.2.4. ADCP configuration summary.

                                  Parameter                                     Cruise
                                                                 N3                 N4               N5
                        Instrument type                    broad-band        narrow-band         broad-band
                        Frequency (kHz)                       153.6              153.6              153.6
                        Transducer pattern                   convex             concave            convex
                        Depth cell length (m)                    4                  4                  4
                        Number of depth cells                    90                 90                60
                        Segment time (minutes)                   5                  5                  5
                        Time between pings (sec)                 I                  I                   I
                        First bin depth (in)                     14                 14                14
                        Transmit pulse length (m)                4                  4                  4
                        Blank after transmit (m)                 4                  4                  4
                        Navigation type                       DGPS               DGPS               DGPS
                        Data recorded                    raw, navigation, raw, navigation, raw, navigation,
                                                          and averaged       and averaged       and averaged







                   3.2.4       XBT Measurements


                   Expendable bathythermograph (XBT) profiles were obtained using Sippican, Inc., T-7 andT-10
                   probes. T10s operate to 200 in and were used at stations in water depths of 200 m or shallower.
                   T7s operate to depths of 760 m and were used at all other stations. The probe type for each XBT
                   deployment which produced usable data, as well as the drop locations, are given in Tables 3.1.3,
                   3.1.6, and 3.1.9 for N3, N4, and N5, respectively. XBT deployment locations are shown in
                   Figures 3.1.1, 3.1.2, and 3.1.3 for N3, N4, and N5, respectively. On N3, there were 101
                   successful XBTs out of 108 launches. On N4, there were 122 XBT launches with ten failures.
                   On N5, 118 XBTs were released with 22 failures. Methods for deployment were detailed in
                   Jochens and Nowlin (1998).

                   XBTs were deployed between CTD stations to increase the spatial resolution of the temperature
                   field to 10-20 km. Except where CTD stations are close together, one XBT was deployed
                   midway between cross-shelf CTD stations. To test whether significant variability exists at very
                   small cross-shelf spatial scales, the number of XBTs deployed between CTD stations on lines
                   I and 5 was doubled on N4. Subsequent analysis confirmed the original spacing was sufficient
                   to resolve the principal energetic cross-shelf temperature scales (Section 2.2). XBTs also were
                   dropped along the I 000-m isobath.











                                                                                                                     47

                    3.2.5      Underwqy Measurements

                    Near-'surface (-3 in) temperature, conductivity, and fluorescence were logged every 2 minutes
                    throughout cruises N3, N4, and N5 using the Serial ASCII Interface Loop (SAIL) system on the
                    RIVGyre. These measurements continued and extended similar data logging during cruises N1
                    and N2 in the first field year. Details on sensors, logging procedures, calibration procedures,
                    and QA/QC of underway measurements were given in the first annual report (Jochens and
                    Nowlin, 1998). During the second year, data were usually logged from port of departure to port
                    of return. Raw data from each cruise generally are better than 99.9% complete for deadhead as
                    well as along designated station lines. The only significant breaks in the SAIL data logging
                    occurred on cruise N4. During the deadhead transit from Gulfport, MS, to DeSoto Canyon,
                    navigation input problems twice locked up the data acquisition system and prevented portions
                    of the SAIL data string from being logged; these hiatus periods were 2157 - 2304 UTC on 13
                    November 1998 and 1717 - 1757 UTC on 14 November 1998. During two other deadhead
                    periods on cruises N4 and N5, flow to the temperature and conductivity sensors slowed or
                    stopped and no data were collected; these hiatus periods were 0505 - 0853 UTC on 13
                    November 1998 and 2251 - 2317 UTC on 16 May 1999. Other down time during N3, N4, and
                    N5 was approximately 2 to 4 minutes per day (loss of one or at most two scans) when the SAIL
                    data computer was backed up. Locations of discrete samples that were filtered for calibration
                    of the flow-through fluorometer data are given in Figure 3.2.2.

                    These underway measurements of near-surface temperature (SST), conductivity (SSS), and
                    chlorophyll fluorescence (SSQ are supplemental to the contractually required data discussed
                    in Sections 3.2.1 through 3.2.4. However, these underway data are useful in fixing the location
                    of river plumes and other confluence and frontal regimes. And, in collaboration with Dr. Frank
                    Muller-Kargei's bio-optical group at USF, the TAMU and USF fluorometers, in tandem,
                    measured sea surface chlorophyll and sea surface disso"lve'd organic matter.

                    3.3 SummM of Field Data Collected

                    A summary of the data collected and scientific participation on the three cruises conducted in
                    this reporting period is given in Table 3.3. 1. Samples taken at the test stations are not included
                    in this tabulation. In addition, visiting researchers on each cruise collected complementary data
                    for use in their individual research programs. Information relative to these complementary
                    programs is given in Table 3.3.2 and described in section 3. 1.










                    48




                                         31 *N
                                                                                                            OR
                                                                          J,



                                         30*N



                                         29'N
                                                                                                        'g
                                                                                                          IN


                                         28*N

                                                   Cruise N3; n=101

                                         27*N
                                            90*W 89*W       88*W    87*W 86*W      85 W    84*W   83*W    82*W


                                         31*N
                                                             at
                                                   Ss


                                         30*N



                                         29*N
                                                                                                          NO

                                         28*N
                                                                                                          _M"
                                                   Cruise N4; n=108

                                         27*N
                                             90*W   89*W 88*W 87*W         86*W    85 %k 84*W     83*W    82*W


                                         31*N

                                                   ss,
                                                     .................


                                         30*N



                                         29*N



                                         28*N                                                             9N

                                                   Cruise N5; n=102

                                         27*N
                                            90*W 89*W 88*W 87*W 86*W               8 %k    84*W   83'W    82*W



                          Figure 3.2.2. Locations of discrete samples filtered for calibration at sea of
                                           flow-through fluorometer data on cruises N3, N4, and N5.
                                                                                                           lall











                                                                                                                     49

                       Table 3.3. 1. Summary of data collection and scientific participation on NEGOM-COH
                                     cruises. Cruise duration and track length represent port-to-port values; the
                                     cross-shelf track is approximately 2742 kin. Numbers from test/supple-
                                     mental stations are excluded.


                                       Description                          N3              N4              N5
                                                                          July/Aug       Nov 1998       May 1999
                                                                           1998
                       Cruise duration (days)                                      13              12              14
                       Cruise track (km)                                       3817*           3815*          4497**
                       Total hydrographic stations                               100               99              103
                       CTD stations, excluding test stations                       98              98              102
                       Nutrient stations                                           98              98              100
                       Oxygen stations                                             98              98              100
                       Salinity stations                                           22              22              48
                       Pigment stations                                            58              59              61
                       Particulate matter stations                                 60              60              61
                       Particulate organic carbon stations                         60              60              61
                       Surface chlorophyll stations                              101             108               102
                       XBT drops (successful/total)                           101/108         112/122          96/118
                       Nutrient samples                                          883             901               925
                       Oxygen samples                                            883             900               925
                       Salinity samples                                          180             167               358
                       Surface bucket salinity samples                               0              0              33
                       Pigment samples                                           169             163               183
                       Particulate matter samples                                181             178               179
                       Particulate organic carbon samples                        118             120               113
                       Surface chlorophyll samples                               101             108               102
                       Underway surface temperature and                        2 min           2 min           2 min
                       conductivity logging
                       Underway surface fluorescence logging                   2 min           2 min           2 min
                       Total scientific party                                      23              22              23
                       NEGOM-COH scientists                                        13              15              15
                       Guest investigators on board                                10               6                8
                       Students (graduate and undergraduate)                       12               9              10
                       Complementary studies                                         7              5                4

                      Gulfport, MS, to Galveston, TX
                       Galveston, TX, to Galveston, TX.











                   50

                          Table 3.3.2 Complementary programs on NEGOM-COH hydrography surveys.


                                      Description                   Wuly/Aug N4November N5M9y1999
                                                                        1998            1998
                     Guest investigators on board or on shore             14              9              8
                     Drifter launches                                     30              24             0
                     XBTs for PALACE float deployments                    4               0              0
                     Current meter mooring work stations                  I               1              0
                     Marine mammal watchers                               4               4              4
                     Sea bird census observers                            2               0              0
                     Altimeter-in situ data trainees                      1               0              0
                     Bio-optical stations                              -2 / day       -2 / day        -2 / day
                     Plankton net tow stations                            15              12             6
                     Flow cytometry samples                               0               0             251





                   3.4         Surninga of Historical and Concurrent Data Assembly


                   Concurrent data sets were identified and assembled, including sea surface height anomaly
                   (SSHA) from satellite altimeter, sea surface temperature from satellite Advanced Very High
                   Resolution Radiometer (AVHRR) sensors, and ocean color from the SeaWiFS satellite.
                   Ancillary data were acquired, including river discharge, surface wind speed and direction, air
                   temperature, surface barometric pressure, frontal passages, and sea level.











                                                                                                                     51

                                         4 DATA QUALITY ASSURANCE AND CONTROL



                    Data processing and quality assurance/quality control (QA/QC) methods for each type of data
                    were presented in the first annual report (Jochens and Nowlin, 1998). Changes to those methods
                    and a summary of the results of QA/QC processing for July 1998 through June 1999 are given
                    in this section. This section includes results from cruises N2, N3, and N4.


                    4.1         Continuous Profile Data


                    The composite plots of CTD temperature versus salinity for cruises N3 (summer 1998) and N4
                    (fall 1998) show good quality results for the continuous sensors (Figures 4. 1.1 and 4.1.2,
                    respectively). Note the seasonal differences for temperatures higher than 18'C and the lack of
                    scatter and the tight fit below 18'C.

                    4.2         Discrete Measurements: Nutrients. OLcyszen. and SalinLty

                    Nitrate versus phosphate concentrations for cruises N2, N3, and N4 are shown in Figure 4.2. 1.
                    The Redfield ratio of 16:1 for N:P is indicated by the line. Note that nitrate values are high
                    relative to this ratio. Several nutrient data points are still under investigation, but many of the
                    unusual points are from areas directly influenced by river discharge.

                    The composite plot of bottle salinity versus CTD salinity for cruises N2 through N4 is shown
                    in Figure 4.2.2. Overall agreement is good, as shown by the r' values of 0.99 for each cruise.
                    Differences occurred mainly in regions with significant vertical gradients of salinity over the
                    depth difference between the bottle sample and the deeper CTD sample, suggesting the same
                    waters were not sampled. These were mainly at near-shore, shallow, river-influenced stations.

                    Dissolved oxygen concentration versus sigma-theta for cruises N2, N3, N4 are shown in Figure
                    4.2.3. The dissolved oxygen concentrations behaved as expected, with most variability in the
                    less dense upper water than in the denser deep water. Note the oxygen minimum at about 27.15
                    or 27. 10 kg-m-3.

                    4.3         Acoustic Doppler Current Profiler Measurements

                    QA/QC processing of ADCP data was described in detail in Section 4.4 of Jochens and Nowlin
                    (1998). A brief summary is given here, with results for cruises N2 through N4.

                    4.3.1       Standard ADCP Proggagn

                    ADCP data are recorded using the RDI TRANSECT software, which also logs the DGPS
                    navigation data to a separate file. TRANSECT records raw binary ADCP data, averages the data
                    into 5 -minute segments, and converts the averaged data into ASCII format. ADCP data next are











                   52







                         33                                            f

                         31 -7


                         29
                                                                         /* .71

                         27-


                         25


                         23- /                                                              7-
                                                                                  .V.


                         21-


                         19


                     F   17 -


                         15-

                                    Of

                         13





                          9


                          7


                          5-


                          3,
                           20     22     24     26      28     30     32      34     36     38
                                                         Salinity




                     Figure 4. 1. 1. Composite potential temperature-salinity diagram for stations from
                                  cruise N3 (July/August 1998). The minimum salinity was 24.715.











                                                                                                              53







                             33    1  71 7 17

                             31



                             29
                                                                     ,It
                                                                     I ,,/
                             27-



                             25



                             23-


                         P   21 -


                             19-1



                             17 -



                          0  15-



                             13






                              9 -



                              7



                              5 -


                              3
                              20      22      24       26      28      30      32      34      36       38
                                                                 Salinity





                        Figure 4.1.2. Composite potential temperature-salinity diagram for stations from
                                       cruise N4 (November 1998). The minimum salinity was 15.236.











                     54









                           33




                           30




                           27-




                           24-




                           21-




                           18




                           15-
                        z



                           12-




                             9-




                             6-




                             3




                             0
                             0.0              0.5               1.0               1.5               2.0
                                                        Phosphate (a M'L-')




                       Figure 4.2. 1. Phosphate versus nitrate for 1998 cruises N2 (spring), N3 (summer),
                                     and N4 (fall). The line represents the Redfield ratio of N:P (16: 1).











                                                                                                          55







                             7j           1111111111111 IT 1111111111111111 11111111111 11111 11 111 1111 111 11111111
                               -  Cruise:      N2     N3    N4
                           36-               0.991 0.994 0.985
                           35-    no. pairs: 189     191    178

                           34--


                           33-


                           32-


                           31 -


                           30-


                           29


                           28-


                           27-


                           26-


                           25


                           24-


                           23


                           22-


                           21-

                             0 1
                             20  21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37
                                                           Bottle Salinity





                       Figure 4.2.2. Ensemble upcast CTD salinity versus bottle salinity for 1998
                                     cruises N2 (spring), N3 (summer), and N4 (fall).











                 56







                      13-111 1111 111111111111111111 11111111111 111-

                      14-

                      15-


                      16-


                      17-


                      18-


                      19


                      20-
                    C1

                      21


                   .bo
                      22-


                      23-


                      24-


                      25-


                      26-


                      27-

                                         I 1 1 17711 1 11 1 11 11 11 1 1
                      28@ 1 1 1 1 1 11
                         1      2      3       4      5       6      7       8      9
                                           Dissolved oxygen (ml, - U')




                   Figure 4.2.3. Dissolved oxygen versus upcast sigma-theta for 1998 cruises
                               N2 (spring), N3 (summer), and N4 (fall).











                                                                                                                   57

                    merged with navigation data. The ship velocity is subtracted from the raw ADCP measurements
                    to obtain the current velocity. DGPS ship velocity is used for the calculation in deep water
                    while bottom-track ship velocity is used in shallow water. That subset of the data having both
                    bottom-track and navigation velocities is used to perform a calibration of the ADCP after the
                    manner. of Joyce (1989). The complex regression statistics for the bottom-track versus GPS
                    navigation velocities and the average DGPS ship speed are summarized in Table 4.3. 1. These
                    show the regression angle and modulus fall within typical values of mean alignment error (1 -2
                    degrees) and sensitivity error (1.00 to 1.04) for the RIV Gyre. After navigation data are merged
                    with ADCP data, data are inspected for additional problems and bad data segments are removed
                    or flagged. The results of this step are summarized in Table 4.3.2.




                           Table 4.3. 1. Complex regression statistics for GPS velocity versus bottom-track
                                         velocity on cruises N2 through N4.


                                  Description                   N2            N3                   N4

                       Stations for misalignment angle         2082          2343                 482
                       Sample size used                         8673         11119                1837
                       Clockwise regression angle (a)        -2.417116      -2.0498              -1.2924
                       Regression modulus (bm)               0.996156      1.000113             1.002139
                       Coherence parameter (pl)               0.96684       0.95039             0.92740
                       Average GPS ship speed (cm-s-1)         466.5         453.5                428.4











                  58


                         Table 4.3.2. Results of evaluation of ADCP data for external factors on cruises
                                       N2 through N4 and number of data segments rejected.


                                            Description                            N2         N3          N4


                     Total number of segments                                      3071        3572         810
                     Segments rejected for no navigation data                          61         65         14
                     Segments rejected for insufficient beams                           0          0         13
                     Segments rejected for bottom-track depth too shallow             43        261            9
                     Segments rejected for slow ship speed (< 100 cm-s-1)            682        640         162
                     Segments rejected for fast ship speed (> 650 cm-s-1)               0          0           0
                     Segments rejected for % of good pings, in first bin < 30          57         49         10
                     Preliminary number of usable segments                         2228        2557         594
                     Segments rejected for bad navigation data                       146        214         112
                     Segments rejected for outliers                                  246        420          66
                     Final number of usable segments                               1836        1923         416





                  4.3.2      New Ensemble Processing Procedure


                  To improve the overall data quality and to recover segment data eliminated because of bad
                  pings, special in-house processing software was developed for the broad-band ADCP. The
                  Ashtech ADU2 3DF positioning antenna array (Section 3.2.3) collected high-precision
                  positioning information that allowed these additional quality control procedures. The array
                  provides more accurate attitude (pitch, roll, heading) information than the ship's Sperry
                  gyrocompass. Ashtech data are used for special processing of the individual 8- to 10-second
                  ensembles that are averaged together to make the 5-minute segments. Ensembles are composed
                  of four 2-second pings, of which two are used for bottom tracking. The remaining two are
                  averaged together to estimate current velocity. In the original processing method, all ensembles
                  are automatically averaged into 5-minute segments for further processing by the TRANSECT
                  software, Our experience with shipboard ADCP data, however, has shown that occasionally one
                  or more ensembles in a segment have unrealistic or bad values that result in the removal of an
                  entire 5-minute averaged segment. By quality controlling and discarding bad ensembles prior
                  to averaging into 5-minute bins, the data quality is substantially increased.

                  The ensemble processing requires high-precision position information, because each 8-second
                  ensemble must be corrected for ship speed as opposed to each 5-minute segment, where it is
                  only necessary to determine the ship@s velocity using the navigation data recorded at the
                  beginning and end of a 5-minute segment. Because the ship moves only a small distance during
                  the ensemble relative to during a segment, it is important to obtain accurate ship positions to
                  within a meter. The ship@s position is recorded by differential GPS at a 1 Hz sampling rate to











                                                                                                                  59

                   get a reliable average ship speed during the 8-second ensemble. To illustrate, consider a ship
                   traveling at 400 cm-s'. The ship would move 32 in during one ensemble, but would move 1200
                   in during one segment. It is easy to see how position resolution of several meters would hardly
                   affect the accuracy of ship velocity during a segment, but could greatly affect the velocity
                   estimateduring an ensemble.

                   After a reliable estimate is obtained for the ship velocity, it is then subtracted from the ADCP
                   transducer velocity to get current velocity in th6 same way as described in Jochens and Nowlin
                   (1998). The resulting current velocity ensembles are then quality controlled using the percent
                   good flag. Because only two-pings are used per ensemble the percent good flag is either 0 - both
                   pings bad, 50 - one good, one bad ping, or 100 - both pings good. Any ensemble less than 100%
                   good is discarded. The resulting quality controlled ensembles are then binned into 5-minute
                   averaged segments. Joyce parameters are also determined.

                   A by-product of the ensemble processing is the ability to quality control ADCP data when the
                   ship is on station. Previously, these data were discarded because of unreliable ship heading and
                   errors in the 5-minute data due to ship acceleration and deceleration when approaching and
                   leaving a station. It is believed that the ensemble proces'sing greatly enhances the quality and
                   reliability of the NEGOM ADCP data set. The ensemble processing also will lead to removal
                   of slow ship speed criterion for excluding segments.

                   Cruise N3 ADCP data have been ensemble processed. Testing and refinement of the ensemble
                   procedures are still in progress.

                   4.3.3       Results of QA/QC for N2 through N4

                   Cruise N2: There were no collection problems during the N2 cruise. The dominant problem
                   encountered was identified during data processing and was caused by a systematic offset in the
                   gyrocompass directional data. A sinusoidal drift in the angular alignment parameter was
                   discovered, The drift was quantified by estimating the mean alignment error for each cross-shelf
                   transect. In this way, the alignment error as a function of ship@s heading was estimated. The
                   misalignment error ranged from 0.5' for a southward heading to -3.6' for a northward heading.
                   The ADCR data then were corrected using this relationship rather than using a single alignment
                   error value for the whole cruise. The problem was caused by excessive wear in the bearings of
                   the gyroscope. A complete refurbishment of the gyrocompass in June 1998 fixed this problem.
                   Data from N3 and N4 were specifically analyzed for reoccurrence ofthis problem and data from
                   NI were reanalyzed to be certain the problem did not exist in those data as well. There was no
                   evidence of this problem during those cruises. There was no heading dependence found for the
                   sensitivity Joyce parameter.

                   Cruise N3: The Ashtech data were recorded separately from the standard navigation stream and
                   'had to be treated separately when merging with the ensemble data, This changed in ftiture
                   cruises when Ashtech data were fed directly into the same file containing the standard











                   60

                   navigation stream. There were no other significant problems with the broad-band data
                   collection or processing.

                   Cruise N4: Early in the cruise the broadband ADCP was damaged (Section 3.2.3). The back-up
                   narrow-band ADCP replaced the broadband after a diver was commissioned to inspect and help
                   remove the broad-band instrument from the instrument well. This occurred near line 4, so only
                   the west portion of the shelf was measured with the ADCP.

                   A 38 kHz broad-band ADCP was loaned to TAMU for testing and placed in the aft moon pool
                   of the RIV Gyre. It was thought that this instrument might supplement the data collection by the
                   150 kHz broadband and provide data to nominally 700 m depth. However, engine noise
                   overwhelmed the acoustic signal. Multiple tests while at sea provided useful diagnostic
                   information for trouble shooting the mechanisms of noise contamination, but no immediate
                   solutions were apparent. Tests included switching the instrument from broad-band mode to
                   narrow-band mode and recording ADCP data at various ship speeds, including adrift with the
                   engines declutched and turned off. No usable data was obtained from the 38 kHz ADCP.

                   4.4        XBT Measurements


                   At the time of deployment, the XBT operator enters an event marker in the GERGNAV
                   navigation computer. This records the LJTC time and DGPS location at the time of the drop in
                   a disk file. The operator also records a bottom depth reading provided by bridge personnel, the
                   location, and the temperature and salinity from the flow-through system on the paper copy of
                   the XBT profile. This hand-written information provides a check against the digital data. The
                   binary format files are converted to ASCII using Sippican software. The ASCII files are plotted
                   and inspected by eye for reasonableness. The first three data points are discarded as they show
                   clear evidence that the probe has not come into equilibrium yet. Data collected after an active
                   probe reaches the seafloor also are removed. While this depth is frequently obvious from the
                   temperature record, corrected fathorneter depths are used to truncate the records when needed.

                   The depths generated by Sippican software are not used for the XBT QA/QC processing.
                   Sippican-generated depths are determined by an old drop-rate formula known to be in error.
                   Newer, more accurate drop rates formulas have been determined empirically by careful
                   comparison between CTD and XBT profiles (e.g., Hanawa et al., 1995). The Hanawa
                   formulation is used to produce a. new depth series for each probe. The corrected fathometer
                   depth is compared to the new depth data to determine where to truncate the data. Standard
                   practice is to report XBT temperature profiles using the provided Sippican generated depths; the
                   users are expected to correct the Sippican depths using the current accepted drop rate formulae.

                   4.5        'UndenLa 'Measurements

                   Chlorophyll computed from fluorescence obtained from a flow-through fluorometer         generally
                   agreed with the extracted chlorophyll to ï¿½0.05 pLg-L-' or better in low chlorophyll, bio-optical











                                                                                                                     61

                    Type 11 environments and to ï¿½ 0.2 gg-1;I or better in high chlorophyll, bio-optical Type I
                    enviroriments on each of cruises N3, N4, and N5. Figures 4.5.1, 4.5.2, and 4.5.3 summarize
                    these calibration data for summer 1998, fall 1998, and spring 1999 cruises. Theexceptionwas,
                    fall cruise N4, when extracted chlorophyll was anomalously lower than flow-through
                    fluorescence at a number of locations in both Type H and Type I water. Three outlier
                    high-fluorescence, low-chlorophyll points were excluded ftom the N4 Type I water calibration
                    curve, and 18 high-fluorescence, low-chlorophyll points were excluded from the N4 Type III
                    water calibration curve (Figure 4.5.2). Some of the high fluorescence at these locations
                    apparently resulted from colored dissolved organic matter (CDOM) as well as from chlorophyll.

                    In general, sea surface chlorophyll (SSQ showed a strong inverse correlation with sea surface
                    salinity (SSS), since low salinity is usually a proxy for high nitrate and phosphate concentrations
                    in surface water of coastal and estuarine origin. On each of cruises N2, N3, and N4 (as well as
                    on cruise N1, summarized in Jochens and Nowlin (1998)), locally low salinity water usually had
                    high chlorophyll, and vice versa. Where SSS was < 32, SSC was usually > 0.5 gg-L-1. The
                    contour plots for cruises N2 through N4, discussed below, illustrate this point.

                    Cruise N2: SSC was low (< 0. 1 gg-L-1) and SSS was high (> 34) seaward of the I 00-m isobath
                    along lines 8 through I I (Figure 4.5.4). This is the region where altimetry (sea surface height
                    anomaly data) and ship data (geopotential anomaly data) show that a secondary warm eddy was
                    present, with weakly anticyclonic (convergent) surface circulation. In contrast, along lines I
                    through 3 to the west was a region of lower SSS, below which the nitracline was often locally
                    shallow as well. In this western part of the NEGOM field region, SSC was two-fold or more
                    higher. Locally highest SSC values (> I jig-L-1) were associated with low SSS flowing out of
                    Mobile Bay, Mississippi Sound, Pass a Loutre, and the South West Pass of the Mississippi River
                    Delta.


                    Cruise NI SSS was lower than 32 along the continental slope throughout the field area, and
                    SSC was generally > 0.5 ptg-L-1 (Figure 4.5.5). Waters with the lowest SSS (27-28) were
                    encountered over the slope along lines 6 and 7. These had SSC concentrations of > I jig-L-1.
                    This low- salinity, high-chlorophyll surface water appears to be Mississippi River water that had
                    been entrained into the anticyclonic circulation about the warm ringlet that was centered over
                    DeSoto Canyon some days to weeks before the cruise. Water with similar SSS and SSC
                    characteristics was encountered close off the Mississippi River Delta on lines 1 and 2, but was
                    no longer spatially coherent with that found along lines 6 and 7 at the time of the survey.

                    Cruise N4: On cruise N4, waters with SSS > 36 were found over most of the slope seaward of
                    the I 00-m isobath along lines 3 to I I (Figure 4.5.6). Although this is quite high for surface
                    salinity and typical of what is usually classed as oligotrophic, open-ocean water, the month of
                    November is the time of year in which the seasonal cycle of SSC in Type IEI water begins to
                    increase (1\4uller-Karger et al., 1991). On this cruise, SSC in this Type II water everywhere
                    exceeded 0.1 ptg-L-', ranging to 0.3 gg-U. The highest concentrations of SSC were found
                    inshore, over the inner shelf of the Florida Bight, off Mobile Bay, and close off the Mississippi











                  62




                          0.5
                                 (a) Type II (low chlorophyll) water

                          0.4-




                          0.3


                       U

                          0.2-
                       CIS    -



                                                                Chl   0.0021504*flc - 0. 19
                          0.1
                                                                n = 34; r' = 0.680
                          0.01 . . .
                            100   120    140    160    180    200    220    240    260    280    300
                                                   SAIL pick-up (millivolts)


                          6.0-

                              -   (b) Type I (high chlorophyll) water
                          5.0-


                          4.0-



                          3.0-
                       U


                       F! 2.0-


                          1.0-                                  Chl   0.0035697*flc - 0.49
                                                                n   68; r= 0.954
                                     r


                            200     400      600     800      1000    1200     1400     1600    1800
                                                   SAIL pick-up (millivolts)


                  Figure 4.5. 1. Flow-through fluorometer calibration for cruise N3 (July/August 1998).











                                                                                   63





                      0.7-
                             (a) Type II (low chlorophyll) water
                      0.6



                      0.5-



                      0.4-                              %

                   U
                      0.3-



                      0.2-

                                       0*   0           0
                                      *0              Chl  0.0028935*flc - 0.29
                      0.1-                            n   65; r' 0.920

                      0.0
                         100     150       200        250     300       350       400
                                            SAIL pick-up (millivolts)


                      4.0

                             (b) Type I (high chlorophyll) water


                      3.0-





                      2.0-
                   U





                      1.0-
                                                      Chl  0.005492*flc - 1.35
                                                      n   22; r' 0.907
                      0.0 @                               I , I      I I I ,, , , ,1
                        200    300    400    500      600   700    800    900    1000
                                            SAEL pick-up (millivolts)


                Figure 4.5.2. Flow-through fluorometer calibration for cruise N4 (November 1998).
                           Diamonds denote outliers that were not used in the calibrations.











                  64





                          0.3 ....
                                    (a) Type I (low chlorophyll) water




                          0.2-



                      U


                       2@ 0.1-

                                                                  Chl    0.001 1634*flc - 0.05
                               -                                  n   5.4; r' 0.623
                          0.01,                                       . . I __ I I....  I.........   I
                             100    110    120     130   140    150     160    170    180    190     200
                                                     SAIL pick-up (millivolts)


                          8.07

                               -    (b) Type I (high chlorophyll)     r
                          7.0-                                  wpl@

                          6.0-


                          5.0-


                          4.0-
                      U


                          3.0-                 /0
                                                                  Chl    0.003713*flc - 0.50
                          2.0-           EY                       n = 44; r= 0.992


                          1.0-                                    Line 1: Chl = 0.0076*flc - 1.43
                                                                  n   4; r'  0.994
                          0.0       0                                  ' I      I .     I , . I I .
                                    .........        .......
                             100    300    500     700   900 1100 1 0 1500            1700 1900     2100
                                                     SAIL pick-up (millivolts)


                  Figure 4.5.3. Flow-through fluorometer calibration for cruise N5 (May 1999).
                                Dashed line is for the Line I data (diamonds).










                                                                                                        65







                       31 *N
                                    s
                                    'R@ R
                                                                                        N,
                                                                 'Pip,
                                                                                             _'Alp
                       30*N
                                                                       ON
                                                                                       8,0" -W
                                                                                         MOMA




                                                             2
                                                                         34
                       29*N                                35         Ar
                                                                35..

                                                           J62 3

                                                                                              M
                       28*N
                                                                        .2



                                                                         tj                 . . . . . .
                                    (a) Salinity                              0
                       27*N                                               S
                         .90*W    89*W     88*W     87*W    86*W     85'W     84*W     83*W    82*W







                       31 *N
                                                    .... . ......
                                                       JI
                                                        F
                                                          Of     IA




                       30'N

                                              @-A
                                                                     0.
                                                          0.

                       29*N



                                                                           01
                       28*N


                                    (b) Chlorophyll a
                       27-N
                          90*W    89*W     88*W     87*W     86*W    85*W     84*W     83*W    82*W





                       Figure 4.5.4. Salinity and chlorophyll a at about 3-m depth on cruise N2 (May 1998).
                                    Salinity observations were from the thermosalinograph; chlorophyll a
                                    was calculated from the flow-through fluorescence.










                66






                     31*N

                                                                -w"

                                                                                'All
                     30*N
                                                                                  "MIN




                     29*N





                     28*N


                                                                                          llql
                                  (a) Salinity
                     27*N
                        90*W    89*W     88*W    87*W     86*W    85*W    84*W      83'W   82*W






                     31 *N

                                                        T",  P"'NO"A
                                                                   'T P



                     30*N                                                                   iB
                                               d..                                @13
                                                     0.5



                                                                                        ","0 M
                     29*N                                                               ig,M



                                                                                          W
                     28*N


                                  (b) Chlorophyll a
                     27*N
                        90*W    89*W     88*W    87*W     86*W    85*W    84*W      83*W   82*W





                    Figure 4.5.5. Salinity and chlorophyll a at about 3-m depth on cruise N3 (July/August
                                  1998). Salinity observations were from the thermosalinograph;
                                  chlorophyll a was calculated from the flow-through fluorescence.










                                                                                                        67






                      31*N
                                                                                            2-
                                                      L
                                                      'ZA!VR
                                                      Z,1@11
                                                      10



                      30-N
                                     A    35

                                                                                      V, M-WOMar,
                                                                                        qz.  "I"

                      29*N




                                                                               35.5
                      28*N -


                                    (a) Salinity                             '00
                      27*N
                         90*W     89*W     88*W      87*W   86*W     85*W     84*W     83*W    82*W







                      31*N

                                                                                           lik W
                                                                                              I  "M



                      30*N

                                                               LQ3


                                                 .3
                                                                                             U
                      29*N                                                                 66    1
                                                                      0. .3




                      28*N

                                                                                    .4

                                    (b) Chlorophyll a
                      27*N
                         90*W     89*W     88*W      87*W   86*W     85*W     84*W     83*W    82*W





                      Figure 4.5.6. Salinity and chlorophyll a at about 3-m depth on cruise N4 (November
                                    1998). Salinity observations were from the thermosalinograph;
                                    chlorophyll a was calculated from the flow-through fluorescence.











                  68

                  River Delta. The SSS and SSC fields on N4 from November 1998 are quite similar to those on
                  NI from November 1997. In both years, SSS < 32 was restricted to the area close-in to the
                  Mississippi River Delta, and SSC seaward of the middle shelf generally ranged between 0.2
                  gg-L-1 and 0.5 gg-l;'.











                                                                                                                    69


                                                    5 TECHNICAL DISCUSSION



                    Section 5 provides a brief technical discussion of forcing functions during cruises N1 through
                    N4 (Section 5. 1) and an overview of the integrated water column chemistry for cruises N I
                    through N4 (Section 5.2). Near-surface in this section refers to data from about the 3.5-m depth.
                    Detailed syntheses and interpretations will be included in the Final Synthesis Report for this
                    project. Although the data shown in this section have received quality control and assessment,
                    they are still preliminary; users should expect that subsequent corrections will be made to the
                    data sets prior to the conclusion of the project. This same caveat applies to all data reported in
                    this document.


                    5.1         Forcina Functions


                    Ancillary data sets are being acquired to allow examination of various forcing functions that
                    influence water properties and circulation in the NEGOM study area. These include
                    meteorological data from marine buoys and coastal land stations, river discharge rates, and sea
                    surface height anomaly fields from satellite altimeters. Some key points regarding the forcing
                    functions at the time of each of the first four cruises are described below. The order of their
                    consideration is wind, river discharge, and eddy-shelf interactions.

                    5.1.1       Wind


                    Meteorological data from offshore buoys and coastal land stations are being acquired. These
                    data include wind speed and direction, air temperature, and barometric pressure. Wind data are
                    treated in two ways: conversion to alongshelf and cross-shelf components and conversion to
                    gridded wind field products. For this report, a description of the preliminary gridded wind fields
                    for the four cruise periods is presented.

                    Hourly winds for November 1997 through November 1998 from 13 sites within and bounding
                    the study area were used to compute gridded hourly winds at 1/2' x 1/2' resolution. Hourly
                    fields of wind components were estimated at each grid point by a statistical optimal,
                    interpolation method. Squared-correlation coefficients confirmed a strong correlation between
                    the observed and gridded components. Monthly mean fields were computed by averaging hourly
                    data over a one-month period at each grid point. Gridded wind vectors at 0700 UTC were
                    produced for each day of the four cruises. Additionally, the Daily Weather Maps of NOAA!s
                    Climate Prediction Center were inspected to identify frontal passages through the NEGOM study
                    area during the cruises. Note this summary of daily wind speeds and directions is limited to the
                    0700 UTC winds.


                    N1: Monthly mean winds were weak(< 5 m-s-1) and generally directed to the south or southwest
                    over the study area in November 1997. Throughout most of the N I cruise, winds were directed
                    to the south and southwest, in response to the presence of high pressure over the continent to the












                    70

                    north.- These winds varied approximately between 5 and 10 m-s-1, with the western shelf
                    experiencing stronger winds than the eastern shelf From November 21-23, however, low
                    pressure was located over the adjacent continent and a front passed over the study area on
                    November 22. The winds in the study area responded mainly by changing their direction to the
                    north and northeast; speeds generally were < 10 m-s-1.

                    N2: In May 1998, monthly mean winds were weak and directed to the northeast. During the
                    N2 cruise, winds were usually 5-10 m-s-I during the first half of the cruise and _-@ 5 m-s-I during
                    the second half They were directed generally between northwest and northeast, although the
                    east shelf experienced winds to the south and southeast in the last half of the cruise. There were
                    several periods with upwelling-favorable (though weak) westerly winds, particularly near-shore.
                    Frontal passages went through the area just prior to the cruise and about May 10- 11, with the
                    winds changing from southerly to northerly.

                    NI Monthly mean winds in July/August 1998 were mixed; in July they were directed
                    east-northeast and were about 3-4 m-s-1, while in August they were directed north-northwest and
                    were < 4 m-s-1. Weak westerly winds occurred during the July portion of cruise N3, when high
                    pressure was over the northeast Gulf During 2-5 August, a stationary front dominated the area
                    with easterly winds -5 to 10 m-s-I in the west and weaker in the east.

                    N4: November 1998 monthly mean winds were weak, particularly in the east area, and generally
                    were toward the southwe    'st to west. Wind directions were variable during cruise N4; speeds
                    ranged from very small to -10 m-s-'. A cold front, moving west to east, passed over the area on
                    21 November. The effect was to shift the direction of the -winds from southerly to northerly as
                    shown in the gridded wind field for 0700 LJTC 21 November 1998 (Figure 5. 1.1 a). Note that,
                    at the time of this plot, the front had just crossed into the far west portion of the study area and
                    the eastern shelf was not yet affected. By November 22nd, the cold front had passed over the
                    area and, with high pressure over the eastern U.S., the winds in the study area had shifted to the
                    southwest at 5 to 10 in -s-I (Figure 5. 1. 1 b).

                    5.1.2       River Discharge

                    Historical river discharge rates were obtained for the larger rivers in the region from the
                    Mississippi River to the Suwannee River. Long-term means of daily discharge were compared
                    with the discharge rates for 1998. During winter 1998, discharge from all rivers in the region
                    exceeded the long-term mean by significant amounts. In spring, the Mississippi continued to
                    discharge at well above its mean rate, as shown in Figure 5.1.2 a (the long-term mean and
                    standard deviation are based on a 64-year record). Other rivers had flows below their means
                    with one significant exception. In late April, rivers from the Pearl to Apalachicola exhibited
                    a brief pulse of much greater than average discharge-in some cases significantly exceeding the
                    mean plus one standard deviation. This pattern is illustrated in Figure 5.1.2 b, showing daily
                    discharge rates for the Tombigbee River; the long-term mean and standard deviation are based
                    on the 70-year record. Major rivers examined east of Cape San Blas generally had only one










                                                                                                              71



                               31*N

                                                                10 . .... .   MU 5!nl-
                                                                              M
                                                                                             "MIN
                               30*N
                                                 DP  1
                                              0

                                                                      C                       Iv . ...... ..
                                     LI                                                                (a)
                                                                                         CD
                               29'9'
                                                                                                     10 M-S-1
                                                                .f420f9
                                                                              At
                                                                             42f6
                               28*N                        or  pr  t               T  +


                               27*N                       Vr-         pr\ N
                                                *- IOL-  #@           9, P@'  K       or  q

                               26*N         4-+-+,                                    +   4    A
                                      001                         4200R,
                                                                                      +

                               25*N
                                  90*W    89*W    88*W   87*W     86*W    85*W    84*W   83*W   82*W


                               31 *N
                                        99 Ssipp
                                                                       Pig



                                                 DP  I
                               30*N

                                                                                    Icr
                                                                                                       (b)
                               29               204
                                                                                                     10 M-S-1
                                                                42 9
                                                                                               Mgo'q
                                                                                                ,g
                                                                                         lel
                               28'W-


                               27*

                                                                                         k-@  k-01
                               26*    A                              A                   el" el k-10
                                                                                         *-I- el k0000
                               25*N -                                                      I       I
                                  90*W 89*W 88*W 87*W 86*W               85*W 84*W       83*W 82*W


                    Figure 5. 1. 1. Wind vector field at 0700 UTC on (a) 21 November 1998 and
                                   (b) 22 November 1998. Triangles indicate NDBC buoy stations;
                                   diamonds C-MAN buoy stations. The 200-m isobath is shown.












           72



              500-

                                                              a


              400



             -0300



             -200


               100



                                             ..............................
                0-
                Jan  Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec


              50

                                                             b


              40




              30-




              20




              10




                0
                Jan  Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec


            Figure 5.1.2. Daily discharge rates for the (a) Mississippi River at Tarbert Landing
                     (64-yr record) and (b) Tombigbee River at Demopolis, AL (70-yr
                     record). Thin solid line shows the long-term mean. Dotted lines
                     show one standard deviation from the mean. Thick solid line shows
                     the 1998 discharge rate.











                                                                                                                  73

                    episode (in March) of very high (relative to the mean) discharge during the first half of 1998.
                    Greater than average river discharge into the Gulf from Mississippi Sound to Cape San Blas
                    during early 1998 is consistent with the extensive surface expression of fresh water observed
                    during cruise N2 in May 1998.

                    5.1.3      Eddy-Shelf Interactions

                    Cyclonic and anticyclonic eddies in deep water near the shelf have profound influence on the
                    outer shelf circulation in the northeastern Gulf, Here are summarized the features present in he
                    SSHA fields during cruises NI through N4. Temporal development of these features was
                    examined through the evolution of sea surface height anomaly (SSHA) over the northeastern
                    Gulf, offshore of the 200-m isobath, using a product prepared by Dr. Robert R. Leben
                    (University of Colorado) based on a combination of altimeter data from TOPEX/POSEIDON
                    and ERS-2. The time series consisted of one SSHA field per week beginning with I October
                    1997 and continuing through 30 December 1998. These SSHA distributions are from data sets
                    that were temporally and spatially smoothed using decorrelation scales of 12 days and 100 km.
                    Therefore, features may appear weaker then they were and smaller scale features may have been
                    removed.


                    Nl: During Nl, an anticyclonic eddy was centered southeast of Southeast Pass and was
                    elongated to extend into DeSoto Canyon (Figure 5.1.3 a). This eddy was responsible for
                    anticyclonic offshore circulation and intrusions of warm, salty water across the western slope
                    and onto the shelf at and west of the Mississippi River Delta (Jochens and Nowlin, 1998). The
                    eastern shelf was under the- influence of cyclonic flow. The strong cyclonic eddy to the south
                    of the anticyclone, may have contributed to the northward advection of warm, salty water along
                    its eastern edge.

                    N2: In spring 1998, the off-shelf area was under the influence of cyclonic flow except for two
                    small anticyclones, one over DeSoto Canyon and another encroaching over the outer shelf edge
                    west of Tampa. Just prior to the N2 cruise, these two small features coalesced; they
                    strengthened during the cruise (Figure 5.1.3 b). Hydrographic and ADCP data taken during N2
                    corroborated these circulation features (Nowlin et al., 1998b).

                    N3: The coalesced feature strengthened during the summer and assumed an east-west
                    orientation in the DeSoto Canyon region. During cruise N3, the anticyclone was centered at
                    about 28.5'N, 87'W and was up against the 200-m isobath at about 88.75'W (Figure 5.1.4 a).
                    The remainder of the outer shelf was under cyclonic flow. The anticyclone and the cyclonic
                    flow to its north induced strong eastward flows along the shelf edge in the western study area.
                    This likely carried the fresh water from the Mississippi River along the shelf edge, leading to
                    a situation with fresher water offshore than nearshore.


                    N4: The eddy remained in the DeSoto Canyon region throughout the fall. In early fall, it
                    weakened and elongated. By the time of cruise N4, it had intensified and developed into the











                  74



                             31 *N




                             30*N


                                                                                          Ne
                                                                                            T
                             29*N

                                                          0


                             28*N


                                                                           0
                                          It
                             27*N                           Z


                             26*N

                                                                                 (a) N 1
                             25*N                                                - I         -- I
                                 90*W 89*W      88'W    87*W   86*W    85*W    84*W 83*W 82*W


                             31*N
                                                                                   U
                                                                      AW


                             30*N




                             29*N                                                             """0



                             28*N



                             27*N        (0
                                                                          -jo



                                                               litI
                             26*N          40ZU
                                                              "N 5          0
                                            0
                                                                                 (b) N2
                             25*N
                                 90*W 89*W      88*W    87*W   86-W 85-W 84-W 83-W 82-W


                  Figure 5.1.3.  Daily sea surface height anomaly (hindcast) from satellite altimeter data for:
                                 (a) 19 November 1997, NI cruise; and (b) 13 May 1998, N2 cruise.
                                 Contour interval is 2.5 cm.










                                                                                                     75



                            31'N
                                     Us& I


                                                                                g,

                            30*N


                                                   .-0                                  ME
                            29*N


                                                                                        M
                                                                                         2
                                                                                         R,
                            28*N                                                       pla

                                  0


                            27*N


                                     -INI   _0
                            26*N                            11@/;@,, Z

                                                                            (a) N3

                            25*N
                               90*W   89*W 88*W 87*W        86*W   85*W 84*W 83*W 82*W


                            31*N              a'

                                                                                       t
                                                                         @45
                                                                          M
                                                                          01 "7
                            30*N
                                                                                         R@




                            29*N
                                                  10
                                                                                        ME



                            28*N


                                                   -ION

                            27-N
                                                                 0
                                    01        j5
                            26*N

                                                                            (b) N4

                            25*N
                               90*W 89*W 88*W 87*W          86*W 85*W 84*W 83*W 82*W


                  Figure 5.1.4. Daily sea surface height anomaly (hindcast) from satellite altimeter data for:
                               (a) 29 July 1998, N3 cruise; and (b) 18 November 1998, N4 cruise.
                               Contour interval is 2.5 cm.












                   76

                   shape with two highs seen in Figure 5.1.4 b. Again the far western study area was influenced
                   by the anticyclone and associated cyclone in the DeSoto Canyon region, while the eastern shelf
                   edge was under the influence of cyclonic flow.

                   5.2         Intep-rated Water Column ChemiLta

                   The water column chemistry component is designed to provide an integrated understanding of
                   the chemistry of the dissolved nutrients, oxygen, salinity, and particulate matter in the area. The
                   dissolved and particulate fractions within the water column are closely coupled through the
                   processes of photosynthesis, excretion, decomposition, and diagenesis. Nutrients (nitrate,
                   phosphate, and silicate), oxygen, and salinity are dissolved water column constituents and are
                   quantified by measuring concentrations. Particulate water column constituents are characterized
                   as living and non-living, organic and inorganic, and phytoplankton-derived. Water column
                   particulate matter is quantified as total mass (particulate matter, PM), particulate organic carbon
                   (POC), and phytoplankton pigments in filtered particulates. The measurement program includes
                   a combination of discrete sampling efforts and continuous monitoring with in situ detectors.

                   The water column chemistry component quantifies and describes how properties are established
                   and altered in space and time in the study area. Observed concentration distributions are the
                   result of inputs, outputs and transformations. Spatial variations in water column properties are
                   observed in three dimensions by sampling regional transects and vertical profiles. The relevant
                   spatial considerations include nearness to shore, proximity to rivers, depth in the water column,
                   and regional location. Temporal variability is assessed by a time-series of sampling cruises
                   three times a year over a three-year period, Seasonality in biological productivity (due to light
                   and nutrient availability) and terrestrial inputs (rainfall and runoff patterns) is well known. The
                   complete dataset will be analyzed to determine the relative importance of biogeochernical and
                   physical processes in controlling and creating variability in water column properties.

                   5.2.1       Temperature

                   In November 1997, near-surface water temperatures were lowest close to shore and isotherms
                   generally paralleled the coast (Figure 5.2.1 a). Offshore termini of transects were -3'C warmer
                   than nearshore waters. Near-surface water temperatures in May 1998 were a few degrees
                   warmer than in November 1997 and exhibited a more complex regional pattern (Figure 5.2.1
                   b). A pocket of colder water was observed along lines 6 and 7 in the mid-shelf area and
                   nearshore along lines 4 and 5. In July-August 1998, near-surface waters throughout the region
                   were wartner by several degrees (-30'C); few regional anomalies were observed (Figure 5.2.1
                   c). Slightly (0.5 to I'C) warmer water was observed at the shoreward ends of lines 9 and 10 in
                   May 1998. By November 1998, regional patterns in near-surface water temperatures exhibited
                   the previous year's onshore/offshore gradients (Figure 5.2.1 d). Within the study area,
                   near-surface waters were -2'C warmer in November 1998 than in November 1997. The mean,
                   standard deviation, and range of temperature for each cruise is given in Table 5.2. 1. These
                   values included temperatures from only the CTD at the times of the bottle trips.










                                                                                                     77






                      31*N
                                                                        "-- Rg
                                                              A


                                                  '19
                      30*N                       20
                                    A             21

                                              22

                                                                           20

                      29*N


                                                                 3


                      28*N
                                                                            23



                                                                     V% tI3
                                   (a) Cruise N 1                  01
                      27*N
                         90*W    89*W     88*W    87*W     86*W    85 W    84*W     83*W    82'W





                      31*N                                -'a

                                                                                           "M
                                                      23
                      30*N

                                                                                            8, W
                                                                                            "N


                      29*N
                                                             23
                                                          24
                                                    4-S

                      28*N


                                   (b) Cruise N2
                      27*N
                         90*W    89*W     88*W    87*W     86*W    @;,Vv,@3 -814,*W 83'W    82*W



                  Figure 5.2. 1. Potential temperature ('C) at 3.5 m on NEGOM hydrographic cruises.
                                Shown are (a) N 1, 16-26 November 1997, and (b) N2, 5-16 May 1998.










               78







                     31 *N
                             . .. .. ..... I. ......... .


                                                           ig
                               , ji


                                                                                  IM,
                     30*N
                                                                                 IN 1,


                                                      30

                     29'N                                                                   N
                                                                                            N




                     28*N


                                  (c) Cruise N3
                     27*N
                        90*W    89*W     88*W    87*W    86*W     85 W    84*W     83*W     82*W







                                                                                           fil
                                                 A
                                                 --alp
                                                 r 0111




                                                          23
                     30'N
                                                                                       M



                     29*N                                    25                          E'@ pffl



                                                                                         IS-
                                                                           Ar
                     28*N                                                                 T*6W


                                                                     2 S
                                  (d) Cruise N4
                                  1                                       00         1    AIR
                     27*N I                                              - ;@@-
                       90*W     89*W     88*W    87*W    86*W     85 %V   84*W     83*W     82*W





                 Figure 5.2. 1. Potential temperature ('C) at 3.5 m on NEGOM hydrographic cruises.
                              Shown are (c) N3, 26 July-6 August 1998 and (d) N4, 13-24 November
                              1998. (continued)











                                                                                                                                               79

                              Table 5.2. 1. Summary of water column temperature, salinity, and dissolved oxygen.


                                           Variable                 N        Mean     Standard Deviation       Minimum        Maximum

                                Potential Temperature ('C)*

                                  All cruises                       3423     19.22            5.67                4.71           32.01
                                  NI                                798      18.09            5.05                4.75           24.30
                                  N2                                865      18.78            4.77                4.71           26.29
                                  N3                                867      20.30            6.87                4.88           32.01
                                  N4                                893      19.61            5.47                4.89           26.09

                                Bottle Salinity

                                  All cruises                       1303     35.51            1.35                20.03          36.67
                                  NI                                782      35.75            0.72                30.47          36.55
                                  N2                                179      35.15            2.04                22.34          36.67
                                  N3                                175      35.02            1.96                25.16          36.57
                                  N4                                167      35.29            1.76                20.03          36.67

                                Dissolved Oxygen (mL-L-')
                                  All cruises                       3414     3.99             0.93                1.90           8.93
                                  NI                                782      4.16             1.07                2.70           6.21
                                  N2                                854      4.09             0.99                2.12           8.93
                                  N3                                878      3.82             0.83                1.90           5.25
                                  N4                                900      3.91             0.81                2.57           5.24


                            CTD values at bottle trips only


                         As expected, near-surface and near-bottom water temperatures in shallow water areas were
                         similar with stratification increasing with increasing water depth. Across the shelf (> -20 in),
                         stratification intensifies as the surface waters warm through the spring and into the summer
                         months. Stratification is modified by local mixing events. Over the four sampling periods, the
                         near-bottom water temperature in water depths below 100 in remained relatively constant with
                         near-bottom water temperatures at 200 in -12 to WC, at 500 m -8 to 10'C, and at 1000 in
                         -5'C (Figure 5.2.2). In waters with bottom depths >200 in, isotherms generally follow
                         bathymetry. At 100 in water depth, there was a gradual increase in near-bottom water
                         temperatures of a degree or two from the first to the last sampling. - In November 1997, a slightly
                         warmer tongue of near-bottom water was observed in the southeastern part of the study area
                         south of Tampa, FL, in the mid-shelf region.

                         5.2.2         Salinijy

                         Salinity varied across the study area (Table 5.2. 1), especially near river discharge points (e.g.,
                         see region near line 1 in Figure 5.2.3). Near surface water salinities increased slightly in the
                         off-shore direction during both November sampling periods by I to 1.5 (Figures 5.2.3 a and d).
                         As with temperature, the near-shore isohaline contours parallel the coastline. Themostobvious










       80



             52 53  54   55 56  57  58  59  60 61
             0      ?1


              26    28     28
              2-4   26
                            26     28 -?0
                22    24
                        22     22


                                        26
            50
                        20     20             <






           100,         -19
             0      50     100      150    200


             52 53  54   55 56  57  58  59  60 61
             0
                    61 ...
                                        30
            50             20    20     31 26
           100             18    IS     13
           150            16 - 16       18
           200                   14
           250                          14

           300                          12

           350                   10

           400

           450

           500                          8
           550

           600

           650

           700
           750

           800

           850

           900

           950

           1000
             0      50     100      150    200
                      Distance along cruise track (km)
             7





















        Figure 5.2.2. Potential temperature ('C) on line 6 of cruise N3, 26 July - 6 August 1998.










                                                                                                     81






                      31*N
                                                                             of
                                                      T oh @V
                                                     1-0  id
                                                     k



                      30*N
                                                  35


                                                              41.             5

                                     3-
                      29*N                34





                                                                                           4@r@" A
                      28*N


                                   (a) Cruise N1
                      27*N
                         90*W    89*W     88*W    87*W     8 V     85@W     84*W    83*W     82*W





                      31*N
                                                           d"41
                                                                                          5



                      30*N
                                          1%    31 31., Jo
                                                            31
                                                                        34
                      29*N                                3@4
                                                             35.5
                                                          j6


                                                                              33
                                                                        3
                      28'N


                                   (b) Cruise N2
                                                                                       0-1> -0,
                      27'N                                  -L-@Ooo
                         90*W     89      88*W     87*W    86*W    85 W     84*W    83*W     82*W





                   Figure 5.2.3. Salinity, from CTD data, at 3.5 m on NEGOM hydrographic cruises.
                                Shown are (a) N 1, 16-26 November 1997, and (b) N2, 5-16 May 1998.











                82







                     31 *N


                                                             60
                                                                    In
                                                                 W
                     30*N



                                                                       3


                     29*N -





                     28*N -



                                  (c) Cruise N3                  *01
                                                                  603
                     27*N --      I    - -1     - I
                        90*W    89*W     88*W    87*W    86*W     8;'@W   84*W    83*W     82*W





                     31*N
                              'Ssf SIPPIIM
                          RA,                                                    M",
                                                                          v
                                                  11W,
                               JI
                                                                           p


                     30'N
                                                                  M

                                                                                       W  R
                                                                                           NO



                     29*N                          36



                                                                         5.5
                                                                                          @A
                                                                                      IRMV
                     29*N

                                                                                         VW

                                  (d) Cruise N4                  Q
                     27*N
                        90*W    89*W     88'W    87*W    86*W     85      84*W    83*W     82*W





                 Figure 5.2.3. Salinity, from CTD data, at 3.5 m on NEGOM hydrographic cruises.
                              Shown are (c) N3, 26 July-6 August 1998 and (d) N4, 13-24 November
                              1998. (continued)











                                                                                                                       83

                    features are the lenses of fresh water emanating from the rivers. For the current sampling
                    period, this was most dramatic in May and November 1998 when salinities lower than 21 were
                    observed near the mouth of the Mississippi River. Away from the river, near-surface water
                    salinity distributions were relatively uniform during the November sampling periods. During
                    the spring and summer sampling periods, near-surface water salinity patterns in the area were
                    more complex. In May 1998, a pocket of lower salinity near-surface water was observed
                    mid-shelf along lines 5 and 6 (Figure 5.2.3 b). This is offset to the northwest from a pocket of
                    cooler water observed at the same time. Salinities were also lower offshore of Mobile Bay due
                    to the outflow of fresh water from the bay into near-surface shelf waters. In the July-August
                    sampling period, a lower salinity pocket of near-surface water was observed above the 500 in
                    isobath along lines 6 and 7 (Figure 5.2.3 c). No corresponding temperature anomaly was
                    detected. Near-bottom water salinities were relatively constant for all four samplings with
                    salinities varying by only I to 1. 5 within the study area. In'the southeastern portion of the study
                    area on the midshelf, near-bottom water salinities consistently show a maximum at -100 m of
                    water depth along lines 9 and 10. Most low salinity anomalies are restricted to a thin veneer of
                    surface water due to density stratification (Figure 5.2.4). During the sampling period the lens
                    of freshwater, when present, was restricted to the top 30 to 50 in and often to the top 10 in of
                    the water column. The extent of vertical mixing depends on the timing of the fresh water
                    intrusion, when sampling occurred, and mixing processes in the area. During periods of riverine
                    inflow, the freshwater plume in near-surface waters was diminished although detectable along
                    line 2.


                    5.2.3       Dissolved OLcyge

                    Dissolved oxygen concentrations in seawater are a balance between oxygen production during
                    photosynthesis, equilibration across the seawater/atmosphere interface, and consumption during
                    aerobic degradation/remineralization of organic matter. Equilibration is only important in
                    surface waters that interact with the overlying atmosphere.               Oxygen production by
                    phytoplankton only occurs in the photic zone where ambient light intensities are high enough
                    and of the right spectral quality to support photosynthesis. Aerobic consumption of oxygen
                    occurs throughout the water column and in sediments where labile organic matter and a viable
                    bacterial community can exist.

                    During most of the sampling period at most locations, the maximum, near-surface dissolved
                    oxygen concentrations are near or above the atmospheric equilibrium value of -5.5 mL-L-'
                    (Table 5.2. 1). Gas solubility varies as a function of temperature and salinity. On occasion,
                    elevated near-surface water dissolved oxygen concentrations were observed due to the local
                    production of oxygen by photosynthesis. Near-bottom water dissolved oxygen concentrations
                    decrease with increasing distance from shore and increasing bottom water depth. Near-bottom
                    dissolved oxygen concentrations in shallow near-shore waters are close to the equilibrium values
                    and decrease to less than 3.0 mL-L-1 in offshore regions. Near-bottom dissolved oxygen values
                    are nearly uniform (-3 to 3.5 mL-L-1) in water depths greater than 100 in (e.g., see Figure 5.2.5).
                    During the sampling period, a low bottom-water oxygen feature was observed between 200- and











                               84



                                                      52             53            54            55               56              57              58            59            60            61
                                                 0
                                                                                                                  32 -                                     30
                                                             3                                                                                                                35
                                                              6                     .5      35                                                                             3S.S
                                                        __,-'-3
                                                                                  36                                                                 35
                                                                                                               36 --------              36        35,s       NO
                                                                                   3
                                                                                   3
                                                                                      .2
                                                                                                              3372                      36.2
                                       E!
                                      -5        50
                                       1=4





                                                                                                          36.4



                                                                                                                                                                                          36...
                                             too    I      -     -      -           I            .     @                                                                                     i
                                                    0                             50                              100                             150                           200


                                                      52             53            54            55               56              57              58            59            60            61
                                                  0    -     36                 36' r6.2r            35           34 0 35-5 M
                                                50                                                          36f -
                                                                                                     6.4
                                             100                                                                                                                                          36.4
                                                                                                            36.2 - 362                                                 36.4
                                             150                                                                                                                                36.4
                                                                                                              6- 36                                                362
                                             200                                                                                                                   36

                                             250                                                                                      35.5

                                             300                                                                                                                   35.5

                                             350

                                             400
                                             450                                                                                                                   35
                                             500

                                             550

                                             600

                                             650

                                             700

                                             750

                                             800

                                             850

                                             900

                                             950
                                            1000    0                              50                             100                             150                           200
                                                                                            Distance along cruise track (km)
                                                                  3@2@



































                                   Figure 5.2.4. Salinity, from CTD data, on line 6 of cruise N3, 26 July-6 August 1998.










                                                     85



               53  54  55  56  57  58   59 60   61 62
              0
               S



                       4.s



                    4




              50
                        V










            100
               0       50      100     150      200


               53  54  55  56  57  58   59 60   61 62
              0
                       4.55
              50        4    4.5 5
            100                3.5          4.5
            150
                                   3
            200                        3
            250

            300

            350

            400

            450

            500

            550

            600

            650

            700

            750

            800

            850

            900

            950

             1000
               0       50      100     150      200
                         Distance along cruise track (km)
               7






               7

















          Figure 5.2.5. Dissolved oxygen (mL.L- 1) on line 6 of cruise N2, 5-16 May 1998.
                 Dots denote bottle locations.











                   86

                   500-m water depth along lines 5, 6, 7, and 8. In the spring and summer, near-shore bottom
                   oxygen I evels become depleted over those observed during the fall and winter sampling period.
                   These depletions are most likely due to the consumption of oxygen during aerobic degradation
                   of sedimentary organic matter. Seasonal variations at shallow water sites coincide with
                   increased exposure of the sea bottom to sunlight. Decreases in dissolved oxygen in the water
                   column below the photic zone are the result of consumption of oxygen during aerobic
                   degradation of particles settling through the water column. Near-bottom dissolved oxygen
                   values can be decreased further by aerobic degradation of sedimentary organic matter.

                   5.2.4       Nutrients


                   Nutrient concentrations and distributions in the study area are controlled by a combination of
                   biogeochemical and physical processes. Processes effecting nutrient concentrations are river
                   discharges, coastal currents and winds, upwelling, biological activity, and rainfall. In
                   near-bottom waters, remineralization of organic matter can lead to elevated levels of nutrients
                   as well. Elevated nutrient levels can support plankton blooms. Nutrient-rich waters often occur
                   in the offshore plumes of the river systems in the area. The interaction of sources and sinks
                   produces seasonal and geographic variations in nutrient distributions. The nutrient component
                   describes spatial, seasonal, and interannual variations in these distributions and examines
                   nutrient distributions in the context of water column stability, river discharge, wind fields, and
                   circulation patterns.

                   Nitrite and urea concentrations were low across the study area and throughout the water column
                   during the sampling period (Table 5.2.2). The concentrations measured were uniform and
                   generally below 0. 10 pM with most values below 0. 05 pM. On average, ammonia mean
                   concentrations were similar (-0. 11 p" for all cruises and varied from 0.0 to 4.48 JIM. In
                   contrast, the major phytoplankton nutrients (nitrate, phosphate, and silicate) showed significant
                   variations with location, water depth, and time of year.

                   Nitrate: Near-surface nitrate concentrations were low (-0. 1 pM) across the study area during
                   the November 1997 sampling. However, in May 1998, near-surface waters exhibited elevated
                   nitrate concentrations (>10 pM) along lines I and 2 (Figure 5.2.6). In August, near-surface
                   water nitrate concentrations were low (-0. 1 pM), with a few exceptions close to the mouths of
                   rivers. In November 1998, nitrate concentrations were again elevated in close proximity to the
                   mouth of the Mississippi, but low east of line 2. Near-bottom water nitrate levels gradually
                   increased with distance offshore and showed similar distributions throughout the sampling
                   period. In general, nitrate concentrations were low throughout the upper 40 to 90 meters of the
                   water column, depending on location and time of year. The deepest nitraclines occurred in
                   November when the upper water column was well mixed. Below the nitracline, nitrate
                   concentrations rapidly increased with water depth to a maximum of 28 to 30 AM to
                   approximately 500 m with relatively constant concentrations in deeper waters (e.g., Figure
                   5.2.6).











                                                                                                                                               87

                                              Table 5.2.2. Summary of water column dissolved nutrients.


                                          Variable                N         Mean      Standard Deviation      Minimum        Maximum

                               Nitrate (pM)
                                  All cruises                     3423      8.61             9.94                0.00            32.88
                                  NI                              794       9AI              10.25               0.00            3112
                                  N2                              1850      8.13             9.55                0.00            32.02
                                  N3                              878       &87              10.07               0.01            30.95
                                  N4                              901       8,10             9.88                0.00            32.88
                               Nitrite (pM)
                                  All cruises                     3423      0,08             0.17                0.00            2.55
                                  NI                              794       0.05             0.07                0.00            0.58
                                  N2                              850       0.11             0.23                0.00            2.03
                                  N3                              878       0.09             0.21                0.00            2.55
                                  N4                              901       0.07             0.14                0.00            1.35
                               Ammonia (pM)
                                  All cruises                     3423      0.11             0.19                0.00            4.48
                                  NI                              794       0.11             0.16                0.00            2.47
                                  N2                              850       0.11             0.18                0.00            1.71
                                  N3                              878       0.14             0.26                0.00            4.48
                                  N4                              901       0.08             0.15                0.00            2.52
                               Urea (@tM)
                                  All cruises                     3398      0.17             0,18                0.00            2.31
                                  NI                              769       0.10             0.13                0.00            L@6
                                  N2                              850       0.28             0.24                0.00            1.61
                                  N3                              878       0.17             0.13                0.00            1.66
                                  N4                              901       0.14             0.16                0.00            2.31
                               Phosphate (VM)
                                  All cruises                     3423      0.51             0.58                0.00            2.03
                                  NI                              794       0.59             0.60                0.00            2.03
                                  N2                              850       0,46             0.55                0.00            1.89
                                  N3                              878       0.53             0.58                0.00            1.91
                                  N4                              901       0.46             0,57                0.00            1.91
                               Silicate (p"
                                  All cruises                     3423      5.83             6,23                0.02            47.84
                                  NI                              794       5.57             6.21                0.03            26.27
                                  N2                              850       6.13             6.18                0.02            28.42
                                  N3                              878       6.53             6.16                0.03            36.30
                                  N4                              901       5,13             6.28                0.02            47.84




                       Phosphate: Near-surface phosphate concentration distributions were similar to those of nitrate.
                       However, elevations in phosphate concentrations near rivers were less dramatic than for nitrate.
                       Near-surface concentrations were low and uniform (Table 5.2.2). Greatest elevations in
                       phosphate concentrations were near the mouth of the Mississippi in November 1998 (contrast the
                       distributions on lines I and 6 on cruise N4 in Figures 5.2.7 and 5.2.8). While near-bottom
                       phosphate values increased with increasing water depth, the increase was much less dramatic










                         88



                                                    84                    83                82                 81                              80
                                         0
                                                     g Lm
                                                                                                                                               I r









                                       50                                                              OS


                                                                                                               2              .5

                                                                                                                    4






                                     100
                                           0                                                                                                50


                                                    84                    83                82                 81                              80
                                         0               -40'.15"Jjj@O     @v 1         041 -                                     U. A -----T -
                                                                                         -1.1'                                            0. 1
                                                                                      6                 2      0
                                        50                                                  0
                                                                                                      Z'"
                                                                                                                                          Lei
                                     100                                    0- 10                                                         6
                                                                                      12                 10                          ff 12
                                     150                                                  14                        12                    14-1
                                                                                                                    14                    16 -
                                     200                                                                            16                    18-1
                                                                                                                    18                    20-
                                     250                                                                       20                         22-
                                                                                                                    22                    2A ---a
                                     300                                                                            ?A                    26-
                                     350                                                                            26
                                     400
                                                                                                                    28
                                     450                                                                                                  28

                                     500
                                                                                                                    28
                                     550

                                     600

                                     650

                                     700

                                     750

                                     800

                                     850

                                     900

                                     950
                                     1000                                                                                                      1

                                                                             Distance along cruise track (km)
                                             7


                                             7


















                             Figure 5.2.6. Nitrate (gM) on line I of cruise N2, 5-16 May 1998. Dots denote
                                                   bottle locations.










                                                                                                                                                               89



                                                    98                    97           96                 95                             94
                                          0

                                                                     0.4                0.2


                                                                              0.1                           ().05




                                                                                 o.C6

                                                                                                                                       0
                                                                                                                                       .0

                                        50


                                                                                                                                       005

                                                                                                      0.05
                                                                           0.05                               0.1                 0.1

                                                                       0.1
                                                                                        0.2 -------                           0.2



                                     100
                                           0                                                                                           50


                                                    98                    97           96                 95                             94
                                         0
                                                                      0.057                                                        0.05
                                        50                                                                              '05
                                                                          0.                                                  0.2
                                                                                             0.05 @*Oj                                 0.1
                                     100                                                               OA                              0.4
                                                                                                 0.6                           0.6
                                     150
                                                                                                         0.;                  - 0.8
                                     200                                                                   L                           I
                                     250                                                                1.2                            1.2
                                     300                                                                     1.4                       IA -

                                     350                                                                      1.6
                                                                                                                                       1.6
                                     400
                                     450                                                                        1.8
                                     500                                                                                 1.8

                                     550

                                     600

                                     650

                                     700

                                     750

                                     800

                                     850

                                     900

                                     950

                                     1000
                                           0                                                                                           50
                                                                           Distance along cruise track (km)
                                                                           005
                                                                       01@
































                             Figure 5.2.7. Phosphate (gM) on line I of cruise N4, 13-24 November 1998. Dots
                                                  denote bottle locations.











                       90



                                         52          53          54        55           56          57           58        59          60         61
                                      0                                                                          a                        I       t






                                                       0.05
                                                          0.1




                                    50




                                                                            0.05

                                                                               0.2


                                                                                                     0.2 11",                   0.1
                                                                                                             Q@
                                  100
                                        0                       50                      100                     150                     200


                                         52          53          54        55           56          57           58        59          60         61
                                      0
                                                                 &
                                    50                              TO            02 10.4                0.05
                                  100                                                0@4:1               0
                                                                                                         h                      ..4
                                  150                                               0.6                  0.6 ------ 9--        0.6
                                                                                                                            0
                                  200                                                                    0.8                       0.8 -0  -------
                                  250
                                                                                                         1.2 ------------         1.2
                                  300                                                                    1.4 --------- ------- 1.4
                                  350                                                                    1.6
                                  400                                                                      1.6                1.6
                           J6     450
                                                                                                                  .9
                           -S     500
                                  550

                                  600

                                  650

                                  700

                                  750

                                  800

                                  850

                                  900

                                  950

                                  1000       . . .
                                        0                       50                      100                     150                     200
                                                                       Distance along cruise track (km)


                          Figure 5.2.8. Phosphate (gM) on line 6 of cruise N4, 13-24 November 1998. Dots
                                                       0*05
                                                          0*7--

























































                                               denote bottle locations.











                                                                                                                    91

                   than for nitrate. Near-bottom water phosphate concentrations were near zero in near-shore
                   waters, increased to 0.8 to 1.2 pM at 200 in, 1.6 to 1.8 gM at 500 in, and >1.6 gM at 1000 m
                   water depth (Figures 5.2.7 and 5.2.8).

                   Silicate: Near-surface water silicate concentrations were often elevated near the Mississippi
                   River and along the Mississippi/Alabama coast (Table 5.2.2; Figure 5.2.9). While near-surface
                   water silicate concentrations were relatively uniform in November 1997, by May 1998 a
                   shelf-wide elevation in silicate concentrations was evident from Mississippi to northern Florida
                   extending seaward to the 100-m isobath. In July-August similar regional elevations were
                   apparent at the mouth of the Mississippi River and offshore of Pensacola, FL. A pocket of
                   silicate-rich surface water was also observed along lines 6 and 7 in August corresponding to the
                   pocket of cooler water previously described. In November 1998, highs in coastal water silicate
                   concentrations were less dramatic but a plume of silicate-rich water was observed seaward of the
                   mouth of the Mississippi River. As with other nutrients, near-bottom water silicate levels
                   paralleled bathymetry. Near-bottom silicate concentrations were -4 to 6 pM at 100 in, -20 pM
                   at 500 m, and 25 ptM at 1000 in water depth (Figure 5.2.9). Silicate concentrations were low in
                   the upper 40 to 100 in of the water column except where freshwater influxes caused elevated
                   concentrations. At some locations, it also appeared that silicate was diffusing from the sediments
                   creating localized, near-bottom anomalies in silicate concentrations.

                   5.2.5       Particulate Matter Distributions


                   Particulate matter in the world oceans is derived from a variety of sources including river
                   discharges, living phytoplankton and bacteria, atmospheric deposition, and detrital remains of
                   organisms. Particulate matter is organic and inorganic and can contain living biological
                   organisms. The living portion of particulate matter interacts with water column chemistry
                   through the uptake of nutrients to form biomass, production of oxygen during photosynthesis, and
                   chemical reactions related to the excretion of waste products and decay of organic detritus.
                   Water column chemistry and particulate matter concentrations and distributions are the end result
                   of these interactions.


                   Particulate distributions can be described in terms of particulate matter, particulate organic
                   carbon, particulate organic nitrogen, planktonic pigments, and light transmission. A summary
                   of particulate properties observed in the study area is given in Table 5.2.3. Vertically continuous
                   estimates of particulate concentrations were provided by transmissometry. Transmissometry
                   records the horizontal and vertical distribution of particles and was used to assess temporal
                   (seasonal and interannual) variability in particle distributions. In the open ocean, most particles
                   are biological organisms and associated detritus. However in near-shore regions, riverine sources
                   of inorganic materials and terrestrial organic matter can be important. Particulate matter
                   concentrations, distributions, and temporal variations are evaluated in the context of water
                   column stability, river discharge, wind fields, and circulation patterns.











              92



                             84          83       82         81                80
                       0











                      50                      2

                                     3
                                                             *2


                                           4                   3





                     100
                        0                                                    50


                             84          83       82         81                80
                       0
                      50                                     2
                                                             =3
                     100                   4                                 3
                                                 5           -4              5
                                              6                5             6
                     150                          7
                     2W                                         7
                                                                             9
                     250                                     9 10            to-
                                                                             12-.
                     300                                                     14-

                     350                                                     16
                                                               16
                     400

                     450
                                                                         20-
                                                                             18


                -5   500
                     550
                     600                                                     22-
                     650                                                     24-

                     700

                     750

                     800                                                     '26

                     850

                     900

                     950
                     1000                                                      1

                                           Distance along cruise track (km)


                Figure 5.2.9. Silicate (gM) on line I of cruise N2, 5-16 May 1998. Dots denote
                            bottle locations.











                                                                                                                                                93

                                              Table 5.2.3. Summary of water column particulate properties.


                                           Variable                      N=        Mean     Standard Deviation       Minimum        Mwdrnurn

                           Transn-@ittance (%)
                                   All cruises                           3475      85.6              7.1                 3.5           92.7
                                   NI                                    798       86.5              53                  7.6           89.4
                                   N2                                    876       85.2              6.6                 24.4          88.9
                                   N3                                    884       85.2              6.2                 27.           88.9
                                   N4                                    917       85.5              9.2                 3.5           92.7
                           Particulate Matter (pg-L-1)
                                   All cruises                           725       467.2             922.6               18.1          10,368
                                   NI                                    180       335.0             612.7               18.5          4,967
                                   N2                                    186       402.3             723.0               18.1          6,418
                                   N3                                    181       552.6             926.7               22.5          9,200
                                   N4                                    178       581.8             1280.5              34.7          10,368
                           Particulate Organic Carbon (gg-L-')
                                   All cruises                           476       73.2              89.2                3.7           730.3
                                   NI                                    118       68.0              51.9                9.4           235.5
                                   N2                                    120       62.7              84.8                6.1           666.9
                                   N3                                    118       115.4             126.1               7.0           730.3
                                   N4                                    120       47.3              61.4                3.7           403.6
                           Particulate Organic Nitrogen (4g-L-')
                                   All cruises                           476       13.0              16.0                0.5           144.0
                                   NI                                    118       11.7              8.9                 1.6           39.5
                                   N2                                    120       11.1              14.2                1.4           108.5
                                   N3                                    118       20.8              23.3                1.3           144.0
                                   N4                                    120       8.7               11.2                0.5           78.1







                         Liaht Transmission: Light transmission was lowest in areas of riverine inputs of particulate
                         matter (e.g., Figure 5.2. 10 shows values on line 1, with its influence from the Mississippi River,
                         from cruise N2). Ninety (90) percent or greater of light is transmitted at most locations
                         throughout the study area with little or no vertical structure evident. Nephelold layers were
                         observed along lines I and 2, and to a lesser extent line 3, indicating outflow of particulate laden
                         water from the Mississippi River during all four cruises. The shallowest stations along lines 7,
                         8, 10, and I I exhibited reduced transmission as well due to outflow of particulate-laden water
                         from the Apalachicola and Suwannee Rivers. Particulate matter concentrations and beam c
                         values were well correlated.











                               94



                                                                84                         83                  82                       81                                     80
                                                   0
                                                                                          0001-@@-             f
                                                                               k5 6!0                                                                                85
                                                                                   0
                                                                                   0







                                                 50






                                                                                                               87.5  --------------------                      87.5
                                                                                                                87.5

                                                                                                              85                   87.5
                                              100      -                                      97.5
                                                       0                                                                                                                   50


                                                                84                         83                  82                       81                                     80
                                                   0
                                                 50                                                                                                  87.5      87.5
                                              100
                                                                                                                       875
                                              150                                                            8 2.5
                                              200                                                                                     '70.5
                                                                                                                                          87.5
                                              250

                                              300

                                              350
                                              400                                                                              7.5                              5
                                                                                                                                               8-7-5-
                                              450                                                                                                   78711-@
                                                                                                                                                       .5
                                              500                                                                                                     Z!%7.5
                                      P4
                                              550

                                              600

                                              650

                                              700

                                              750

                                              800

                                              850

                                              900

                                              950
                                              1000                                                                                                                          5  10
                                                                                               Distance along cruise track (km)


                                    Figure 5.2. 10. Light transmission                                        660 mn wave length; 25-cm. path length) on line I
                                                                 of cruise N2, 5-16 May 1998.











                                                                                                                      95

                    Particulate Matter: Discrete samples for determination ofparticulate matter (PM) concentrations
                    were taken in near-surface and near-bottom waters. The amount and distribution of PM in the
                    study area differed depending on the sampling period. During November 1997, near-surface
                    water PM concentrations were highest near the mouth of the Mississippi River (lines I and 2),
                    and offshore of Apalachicola (lines 7 and 8; Figure 5.2.11 a). Near-surface water PM was
                    elevated across the Mississippi/Alabama shelf and extending out to the 500 m isobath.
                    Near-surface water PM concentrations near the Mississippi River where nearly twice as high as
                    offshore Apalachicola. The plume of PM laden near-surface water offshore of Apalachicola
                    extended over the relatively shallow shelf area to bottom water depths of 100 m. Away from
                    riverine inputs, near-surface water PM concentrations were generally less than 200 Rg-L-1. In
                    May, near-surface water PM concentrations were elevated across a wide expanse ofthe shelf-area
                    within the study area (Figure 5.2. 10 b). Near-surface water PM observed offshore of the
                    Mississippi River were quite high (>200 gg-l;') and the PM laden water was broadly distributed
                    across the Mississippi Bight region. During July-August, near-surface water PM distributions
                    exhibited more complex patterns (Figure 5.2. 10 c). In November 1998, the riverine influences
                    were again recognizable, but a secondary enhancement in PM was also apparent in the central
                    shelf region of the area (Figu re 5.2. 11 d). During all samplings, near-surface concentrations
                    tended to decrease with distance offshore.


                    Bottom water PM distributions generally mirrored the surface distributions but were at lower
                    concentrations. Near-bottom water PM concentrations were elevated near rivers and across shelf
                    areas that exhibited high near-surface wate  'r PM concentrations. For water depths greater than
                    200 m, bottom PM values were generally uniform and less than 300 @tg-L-1. Bottom PM values
                    continued to decrease to 100 @tg-L-' or less at water depths of 500 m or more. Near-bottom water
                    PM-laden plumes were evident near the Mississippi River out to bottom water depths of 1000 m.

                    Particulate Organic Carbon: As mentioned above, particulate matter can be organic or inorganic
                    in origin and living or dead. As a first indication of the origins 6f PM, particulate organic carbon
                    (POC) content was measured in near-surface and near-bottom waters. Unlike PM, there is no
                    detector that specifically determines POC content by in situ measurement. However, when the
                    inorganic content of PM is low, transmission can be used to estimate POC. POC in near-surface
                    waters accounted for.2.5 to 100% of the PM during the sampling period. In general, POC in
                    near-surface waters accounted for 25 to 40% ofthe PM while in near-bottom water POC was only
                    about 7 to 20% of the PM. This is indicative of phytoplankton productivity in the shallow water
                    photic zone and remineralization of organic carbon in the water column. Near-bottom
                    particulates also may have a contribution from resuspended, relatively organic carbon-poor
                    sediments.


                    As for PM, regional patterns in POC differ greatly in time (compare Figures 5.2.12 a and b and
                    Figures 5.2.12 a and d). In general, POC concentrations decrease with increasing distance from
                    shore. POC in near-surface waters over areas with bottom depths less than 100 m generally
                    exceeded 100 gg-L-1. In deep water, near-surface water POC concentrations were usually less










               96







                     31*N
                                                                                 PRIM,'
                                                                            X
                                                                       IN


                     30*N


                                                                                    W
                                                                                    Q'I
                                                                     300
                     29*N                               100



                     28*N



                                  (a) Cruise N1
                                                                  &0      00
                     27*N I     - I - - - I ---                     3 S _i,@ -x I           -
                       90*W     89*W    88*W     87*W    86V     -8?vV' 84-W       83-W    82-W





                                                                                         "'BIN
                                                     'T
                     31 *N
                                 "ip, ..... ... ......
                            WY


                     30*N

                                                                                   VISION&,
                     29*N                                             -300


                                                                        -100

                     28*N



                                                                 ,Olt
                                  (b) Cruise N2                   ï¿½R
                                                                  E905
                     27*N
                        90*W    89*W    88*W     87*W    86*W--- -8;'V 84*W        83*W    82*W



                 Figure 5.2.11. Particulate material ([Lg.L-1) at 3.5 m on NIEGOM hydrographic cruises.
                                Shown are (a) N1, 16-26 November 1997, and (b) N2, 5-16 May 1998.










                                                                                                     97






                      31*N
                                                                                         HIM
                                                I'M


                      WIN





                      29*N





                      28*N


                                   (c) Cruise N3                                      V3
                      27*N
                        90*W     89'W     88*W    87*W     86V     85W     84*W     83*W     82*W






                      31*N
                                ,,@I$ !ppj
                                             TN,170



                      30*N





                      29*N


                                                                                   300


                      28*N                                                                  M



                                   (d) Cruise N4
                      27-N                                  L
                        90*W     89*W     88*W    87*W     86-W    85 W     84-W    83*W     82*W




                  Figure 5.2.11. Particulate material (Rg-L-1) at 3.5 m on NEGOM hydrographic cruises.
                                 Shown are cruises (c) N3, 26 July-6 August 1998 and (d) N4, 13-24
                                 November 1998. (continued)










               98






                     31-N



                                                                                       @W, 'eq
                     30*N


                                                           60


                                                                                       "g.
                     29*N                                          *0
                                                                                        IN



                                                                                         IMs
                     28*N


                                 (a) Cruise N1                           00
                                                                                    I    RPM
                     27*N                                                 ;pI-
                                                                  `@W    84*W     83*W    82*W
                       90*W     89*W    88*W    87*W     86*W    85







                     31*N
                                        Ab                             "I G0 t M'
                                                                                   MMARe


                     30*N
                            A;                                      , ONO--
                                                     0'
                                                                                  @p,
                                                                                     I SM.. IW,
                                                                  70
                     29*N



                                                                        -0
                                                                     70

                     28*N


                                 (b) Cruise N2                   ï¿½R
                                                                 6       00
                                                                  103
                     27*N                                         ;@,
                       90*W     89*W    88'W    87*W     86*     85 W    84*W     83*W    82*W




                 Figure 5.2.12. Particulate organic carbon (gg-L-1) at 3.5 m on NEGOM hydrographic
                               cruises. Shown are cruises (a) NI, 16- 26 November 1997, and
                               (b) N2, 5-16 May 1998.










                                                                                                    99






                      31*N
                                                     F1

                                                    g,@ p


                      30*N


                                                               "CIO ra   100
                      29*N
                                                                                          N,


                                                                      4?0

                      28*N


                                   (c) Cruise N3                  0
                      27*N
                        90*W     89*W    88*W     87*W    86 W    8        84*W    83'W    82*W







                      31 *N      ....... .....
                                                                                           n5i




                      30*N


                                  f                         ilo

                                                                      80
                      29*N                                             60




                                                                            VO
                      28*N



                                   (d) Cruise N4
                                                                                      0
                      27*N .       I   -   I                                              - 11
                        90*W     89*W    88*W     87*W    86*W    85 W     84*W    83*W    82*W




                  Figure 5.2.12. Particulate organic carbon (gg-L-1) at 3.5 m on NEGOM hydrographic
                                cruises. Shown are cruises (c) N3, 26 July-6 August 1998 and
                                 (d) N4, 13-24 November 1998. (continued)











                  100

                  than 100 @ig-l:', The highest POC levels were associated with high PM plumes at river mouths.
                  In many instances, high POC values were broadly distributed across the shelf-indicative of an
                  in situ phytoplankton origin (e.g., compare Figure 5.2.12 c with Figure 5.2.13 c in Section 5.2.6).
                  As a percentage of PM, POC in river plume PM was reduced since most of the riverine PM was
                  inorganic in origin. POC can also be enhanced at in river plumes due to the elevated nutrients
                  supporting enhanced primary productivity. However, a decrease in light availability in high PM
                  waters can inhibit primary productivity as well.

                  POC concentrations in near-bottom waters generally paralleled POC distributions in the
                  near-surface waters. Near-bottom water POC concentrations generally decreased with increasing
                  distance offshore and increasing water depth. Near-bottom POC concentrations in deeper water
                  (>I 00 in) were significantly less than those of near-surface water as a result of remineralization
                  of organic matter during transport through the water column. In shallower water, near-bottom
                  water POC often exceeded POC in near-surface waters probably due to the primary productivity
                  maxima being below the near-surface water depth of collection. At some locations, resuspension
                  of organic-rich sediments may be occurring.

                  5.2.6       PhZoplankton Pigments

                  Chlorophyll and carotenoid pigment distributions are used to infer spatial and temporal variations
                  in phytoplankton biomass and taxonomic composition. Phytoplankton exert an important
                  influence on water column properties. Phytoplankton are an important source of particulates,
                  they produce oxygen during photosynthesis, and they fix water column nutrients into biomass.
                  The composition of particulate pigments provides insight into the relative abundance of algal
                  groups. The plant pigment concentrations and distributions are used to describe the spatial,
                  seasonal, and interannual variations in phytoplankton cominunities; calibrate in vivo fluorescence
                  measurements; and examine phytoplankton communities in the context ofwater column stability,
                  river discharge, wind field, and circulation patterns.

                  Chlorophyll a: Chlorophyll a concentrations are an indication of how much particulate matter;
                  and specifically POC, is living phytoplankton. As an estimate, phytoplankton biomass can be
                  calculated by multiplying chlorophyll a concentrations by 250. However, many factors affect
                                                                                                         -quantitative
                  the chlorophyll a to cellular carbon ratio in phytoplankton, so this conversion is semi
                  at best. Chlorophyll a was measured in near-surface waters, at the water column fluorescence
                  maxima as indicated by in situ fluorometry, and at the base of the photic zone. Discrete samples
                  were also used to calibrate the in situ fluorometer to calculate chlorophyll a concentrations at
                  locations where discrete samples were not taken. A summary is given in Table 5.2.4.

                  In general, near-surface chlorophyll a concentrations were similar to the maximum
                  concentrations in vertical profiles (Table 5.2.4; Figure 5.2.13). In contrast to PM and POC
                  distributions, chlorophyll a was relatively uniformly distributed across the shelf regions of the
                  study area. Elevated chlorophyll a values were associated with discharges from the smaller











                                                                                                                                            101

                                     Table 5.2.4. Summary of water column particulate pigment concentrations.

                                      Variable (TTF)                  N         Mean     Standard Deviation       Mini mum       Maximum
                            Chlorophyll a
                                  All cruises                         672       402.3             731.4               0.0            12,229
                                  NI                                  169       336.8             461.9               14.3           3,889
                                  N2                                  177       484.7             716.0               0.0            4,175
                                  N3                                  168       573.4             1137.9              40.3           12,229
                                  N4                                  162       205.2             183.1               14.9           1,350
                            19-Butanoyloxyfucoxanthin
                                  All cruises                         672       28.3              71.0                0.0            1,678
                                  NI                                  169       25.9              24.6                0.0            164
                                  N2                                  173       22.6              35.5                0.0            169
                                  N3                                  168       24.1              30.5                0.0            13
                                  N4                                  162       41.5              133.5               0.0            1,678
                            Fucoxanthin
                                  All cruises                         672       59.2              146.0               0.0            1,872
                                  N1                                  169       35.2              56.3                0.0            316
                                  N2                                  173       85.0              206.3               0.0            1,336
                                  N3                                  168       91.7              181.4               0.0            1,872
                                  N4                                  162       62.6              64.0                0.0            350
                            19-hexanoyloxyfucoxanthin
                                  All cruises                         672       82.5              69.0                0.0            627
                                  NI                                  169       55.4              38.5                0.0            193
                                  N2                                  173       94.6              76.6                0.0            388
                                  N3                                  168       116.3             72.1                0.0            430
                                  N4                                  162       62.6              64.0                0.0            627
                            Diatoxanthin
                                  All cruises                         672       4.1               22.2                0.0            232
                                  NI                                  169       1.2               7.4                 0.0            79.7
                                  N2                                  173       12.5              40.8                0.0            232
                                  N3                                  168       2.1               10.0                0.0            73.8
                                  N4                                  162       0.0               0.3                 0.0            3.7
                            Zeaxanthin
                                  All cruises                         672       56.2              235.2               0.0            5,328
                                  NI                                  169       34.9              31.3                0.0            141
                                  N2                                  173       60.1              116.3               0.0            1,092
                                  N3                                  168       126.1             446.4               0.0            5,328
                                  N4                                  162       1.8               5.6                 0.0            44.8
                            Chlorophyll b
                                  All cruises                         672       86.5              109.0               0.0            745
                                  NI                                  169       70.6              65.2                0.0            289
                                  N2                                  173       74.3              107.6               0.0            606
                                  N3                                  168       142.4             142.6               0.0            745
                                  N4                                  162       58.2              84.3                0.0            484











               102




                     31*N                                                          'na."M
                                FIM
                                                    Am


                           F5

                     30*N



                                          2


                     29*N
                                                                     3




                     28*N


                                 (a) Cruise N1                  110- 'j,
                     27*N
                       90*W     89*W    88*W     87*W    86 W    8;'V'@ 84*W      83*1W   82*W




                     31*N
                                           .. ........&





                     30*N



                                                                             @600

                     29*N

                                                                              400


                     28*N                                         100


                                  (b) Cruise N2
                     27*N
                       90*W     89*W    88*W     87*W    86*W    85 %V   84'W     83*W    82*W




                 Figure 5.2.13. Chlorophyll a (ng-L-1) at 3.5 m on NEGOM hydrographic cruises. Shown
                                are cruises (a) N1, 16-26 November 1997, and (b) N2, 5-16 May 1998.










                                                                                                  103






                     31*N
                                                              WI MM'
                                                                "All
                              RIM,
                               i3s
                                fisi
                                                              W@@Ha"k@
                                    4112


                                                                                       XRI@
                     30*N                                              13
                                                             400



                     29*N
                                                                         2%


                                                         X.


                                                                   2
                     28*N


                                  (c) Cruise N3
                     27*N
                        90*W    89*W    88*W     87*W    86*W     85 W    84*W     83*W    82*W







                     31 *N


                                                                                       owl
                     30*N                                                              BE

                                                                             N


                                                           2
                     29*N                              100              200
                                                                     IGb




                     28*N -



                                                                 'e.' un
                                  (d) Cruise N4
                                                                         00
                     27*N
                        90*W    89*W    88*W     87*W    86*W    85 W     84'W     83*W    82*W




                 Figure5.2.13. Chlorophyll a (ng-L-1) at 3.5 m onNEGOM hydrographic cruises. Shown
                                are cruises (c) N3, 26 July-6 August 1998 and (d) N4, 13-24 November
                                1998. (continued)











                   104

                   rivers that carry moderate PM loads and nutrient-rich waters. Regionally, near-surface
                   chlorophyll a concentrations differed during each sampling period with highs in the southeast
                   region in November 1997 (Figure 5.2.12 a), along the Mississippi Bight in May 1998 (Figure
                   5.2.12 b), off the Mississippi River in July-August 1998 (Figure 5.2.12 c), and a uniform
                   distribution in November 1998 (Figure 5.2.12 d). Chlorophyll a concentrations varied over a
                   wide range in some seasons and were uniform in others. In general, near-surface water
                   chlorophyll concentrations decreased with distance offshore. The subsurface fluorescence
                   maxima chlorophyll a concentrations were similar to those in near-surface waters.

                   Accessory Pigments: Predominant accessory pigments detected were
                   19-butanoyloxyfucoxanthin, fucoxanthin, 19-hexanoyloxyfucoxanthin, chlorophyll b, c, c,
                   zeaxanthin, and 0-carotene (Table 5.2.4). Other accessory pigments that were present in trace
                   amounts included violaxanthin, peridinin, prasinoxanthin, diadioxanthin, diatoxanthin and
                   alloxanthin. It is informative in assessing the taxonomic make-up of phytoplankton commun-
                   ities from pigments to ratio the concentrations of each accessory pigment to chlorophyll a.

                   19-butanoyloxyfucoxanthin (19-but) is a pigment diagnostic of pelagophytes. The ratio of
                   19-but to chlorophyll a (19-but/chla) was similar during May and July-August 1998. High
                   19-but/chla ratios were observed along lines 9, 10, and I I with ratios as high as 0.23. Offshore
                   regions near lines 7 and 8 exhibited 19-but/chla ratios as high as 0. 10 in May and July-August
                   1998. Throughout the rest of study area, 19-but/chla ratios were mostly below 0.05. During the
                   two November samplings, 19-but/chla ratios were similar. Concentrations of 19-butanoyloxy-
                   fucoxanthin in the near-shore regions between line 3 and 7 in November 1997 and 1998 and in
                   the offshore regions between line 9 and I I in May and July-August 1998 suggest that
                   pelagophytes were important members of the phytoplankton community.

                   High concentrations of fucoxanthin in combination with diadinoxanthin, diatoxanthin, and
                   0-carotene indicate the presence of diatoms. Fucoxanthin to chlorophyll a ratios (fuco/chla)
                   were similar in May and July-August 1998 ranging from 0. 15 to 0.6. Fuco/chla ratios were low
                   in the offshore region (below 0.2). Fuco/chla ratios were similar for both November samplings
                   in near-shore coastal regions throughout the entire study region with ratios as high as 0.4. In
                   November 1997 and 1998, fuco/chla ratios were below 0.05 in most offshore areas.

                   High concentrations of chlorophyll c, and c, fucoxanthin, diadioxanthin, and P-carotene indicate
                   that prymnesiophytes are an important phytoplankton group. 19-hexanoyloxyfucoxanthin to
                   chlorophyll a (19-hex/chla) ratios throughout the study area were as high as 0.9. For the
                   November samplings, 19-hex/chla ratios in near-shore regions between lines 3 and 5 and lines
                   11 and 10 were as high as 0. 5. The ratios were lower throughout the rest of the study area. The
                   ratio of 19-hex/chla in May and July-August 1998 was as high as 0.9. Diadinoxanthin to
                   chlorophyll a ratios (diad/chla) were high in the near-shore regions of lines 8 through 11 and I
                   and 2 in November 1997, May 1998, and November 1998. Diad/chla ratios were as high as 0.7.
                   The high concentrations of 19-hex/chla ratios and diad/chla observed during all four cruises,
                   particularly along lines 3, 5, 10, and 11, indicates abundant prymnesiophytes.











                                                                                                                    105


                    High zeaxanthin to chlorophyll a ratios (zea/chla) are indicative ofthe presence of cynobacteria.
                    Zea/chla ratios in November 1997, May 1998, and July-August 1998 were as high as 0.9.
                    Zea/chla ratios were low in November 1998 ranging from 0.0 to'O. 1. Chlorophyll bla ratios
                    were highest in November 1997, and in July-August 1998 were as high as 0.50. Therewerehigh
                    chlorophyll b concentrations located in the central part of the study area between lines 8 and 10
                    during all sampling periods.

                    The major plankton groups in the study area are prymnesiophytes, pelagophytes, diatoms,
                    cynobacteria, and prochlorophytes. The presence of only trace amounts of alloxanthin,
                    peridinin, violaxanthin, prasinoxanthin and lutein in near-surface samples indicates that
                    chrysophytes, cryptophytes, dinoflagellates, prasinophytes, and chlorophytes were not significant
                    components of the phytoplankton community. There was little vertical variation in pigment
                    compositions suggesting that phytoplankton composition was relatively uniform throughout the
                    photic zone.

                    5.2.7       Integration of Water Column ProMrties

                    Integration of all the data collected aids in elucidating the importance of biogeochemical and
                    physical processes in producing the observed spatial and temporal variations in the dissolved
                    and particulate constituents of the water column in the study area. The water column study was
                    designedto: (1) examine the relationship between dissolved oxygen, PM, POC, nepheloid layers,
                    nutrients, phytoplankton pigments, and plankton community structure; (2) determine the origins
                    of PM, POC, and nepheloid layers; and (3) estimate the importance of physical and
                    biogeochernical maintaining or changing the observed patterns. As an initial approach, all water
                    column properties were cross-correlated. Correlation coefficients were calculated for every
                    combination of the variables measured. Several expected trends are apparent from the
                    correlation matrix.


                    Potential temperature is positively correlated with time and location variables as expected.
                    Temperature varies as a function of time year (cruise), distance from shore (station number),
                    depth in the water column, and total depth of the water column. In contrast, salinity negatively
                    correlates with nutrient and particulate matter concentrations. Salinity positively correlates with
                    transmission in that transmission is inversely related to the concentration of particulates in the
                    water column. These correlations are in response to the input of nutrient-rich, particulate-laden
                    fresh water from rivers in the study area. Particulate and dissolved silicate concentrations are
                    positively correlated (>0.8) with salinity. Phytoplankton pigment concentrations are negatively
                    correlated with salinity with some being more highly correlated than others (0-carotene,
                    diadioxanthin, and alloxanthin).

                    Dissolved nutrients are positively correlated with each other and negatively correlated with
                    salinity. As expected nitrate, nitrite, urea and ammonia concentrations are intercorrelated.
                    Nutrients are also positively correlated with particulate properties (PM, POC). However,











                   106

                   nutrient concentrations are only moderately correlated with phytoplankton pigment
                   concentrations suggesting that a significant non-living particulate matter source effects
                   particulate distributions in the study area (i.e., the overriding influence of river discharges).
                   Phosphate is highly correlated with the nitrogen containing nutrients reflecting a link both in
                   uptake and remineralization. Phosphate positively correlates with silicate but to a lesser degree
                   than for nitrate suggesting some independence in the origins of these nutrients. Silicate is
                   negatively correlated with salinity and positively correlated with the nitrogen containing
                   nutrients. Due to the co-occurrence of PM in river discharges, silicate is highly correlated with
                   particulate properties, especially PM.

                   Particulate properties (PM, POC, chlorophyll a) were also closely correlated. As above,
                   particulate properties were positively correlated with nutrients and negatively correlated with
                   salinity and transmission reflecting riverine inputs. In general, PM was more highly correlated
                   with these variables than POC reflecting the dual origin ofPOC and the predominately inorganic
                   .composition of PM in riverine discharges. PM and POC positively correlated with chlorophyll
                   a concentrations with POC being more positively correlated than PM. Chlorophyll a was
                   positively correlated with other phytoplankton pigments as expected. In most instances,
                   phytoplankton pigments were intercorrelated with each other with a few exceptions.











                                                                                                             107


                                                    6 LITERATURE CITED



                   Hanawa, K., P. Rual, R. Bailey, A. Sy, and M. Szabados. 1995. A new depth-time equation for
                         Sippican or TSK T-7, T-6, and T-4 expendable bathythermographs (XBT). Deep-Sea Res.
                         1., 42(8):1423-1452.

                   Jochens, A.E., and W.D. Nowlin, Jr. 1998. Northeastern Gulf of Mexico Chemical
                         Oceanography and Hydrography Study between the Mississippi Delta and Tampa Bay,
                         Annual Report: Year 1. OCS Study MMS 98-0060. U.S. Department of the Interior,
                         Minerals Management Service, Gulf of Mexico OCS Region, New Orleans, LA. 126 pp.

                   Joyce, T.M. 1989. On in-situ'calibration'of shipboard ADCPs. J Atm. Ocn. Tech., 6:169-172.

                   Knap, A.H., A.F. Michaels, D. Steinberg, F. Bahr, N. Bates, S. Bell, P. Countway, A.R. Close,
                         A.P. Doyle, R.L. Dow, F.A. Howse, K. Gundersen, R.J. Johnson, R. Kelly, R. Little, K.
                         Orcutt, R. Parsons, C. Rathbun, M. Sanderson, and S. Stone. 1997. BATS Method
                         Manual, Version 4 (April 1997). U.S. Joint Global Ocean Flux Study, Bermuda Atlantic
                         Time-Series Study. 136 pp.

                   Muller-Karger, F.E., J.J. Walsh, R.H. Evans, and M.B. Meyers. 1991. On the seasonal
                         phytoplankton concentration and sea surface temperature cycles of the Gulf of Mexico as
                         determined by satellites. J. Geophys. Res., 96:12,645-12,665.

                   Nowlin, W.D., Jr., A.E. Jochens, R.O. Reid, and S.F. DiMarco. 1998a. Texas-Louisiana Shelf
                         Circulation and Transport Processes' Study: Synthesis Report, Volume 1: Technical
                         Report. OCS Study MMS 98-0035. U.S. Department of the Interior, Minerals
                         Management Service, Gulf of Mexico OCS Region, New Orleans, LA. 502 pp.

                   Nowlin, W.D., Jr., A.E. Jochens, M.K. Howard, and S.F. DiMarco. 1998b. Nearshore bottom
                         properties over the northeastern shelves of the Gulf of Mexico as observed during early
                         May 1998. Texas A&M University Oceanography Tech. Rpt. No. 98-3-T, College Station,
                         TX. 64 pp.






                                                                                                                                                                           Form Approved
                                                  REPORT DOCUMENTATION PAGE                                                                                                OMB No. 0704-0188
                           Public reporting burden for this collection of information is estimated to average 1 our per response including the time for reviewing instructions. searching existing data sources
                           gathering and maintaing the data needed. and collecting and reviewing the collection of information. Send comments regarding this burden estimate or any other aspect of this
                           collection of information. including suggestions for reducing this burden to Washington Headquarters Services. Directorate for information Operations and Reports. 1215 Jefferson,
                           Davis Highway Suite 1204, Arlington.VA 22202 4102 and to Office of Management and Budget. Paperwork Reduction Project (0704.0188). Washington, DC 20503
                                                                                                                        3.REPORT TYPE AND DATES COVERED
                           1. AGENCY USE ONLY (Leave blank)                        2. REPORT DATE
                                                                                         September 1999                 [annual report; Jul 1998 - Jun 1999
                           4.TITLE AND SUBTITLE                                                                                                             5. FUNDING NUMBERS
                                Northeastern Gulf of Mexico Chemical Oceanography and                                                                           C-1435-01-97-CT-30509
                              Hydrography Study; Annual Report: Year 2


                           6. AUTHOR(S)
                              Ann E. Jochens.
                              Worth.D. Nowlin, Jr.


                           7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES)                                                                                8. PERFORMING ORGANIZATION
                              Texas.A&M Research Foundation                                                                                                      REPORT NUMBER
                              NEGOM Program Office
                              Texas A&M University, MS 3146
                              College Station TX 77843-3146


                           9. SPONSORING I MONITORING AGENCY NAME(S) AND ADDRESS(ES)                                                                         10. SPONSORING/ MONITORING
                              U.S. Dept of the Interior                                                                                                           AGENCY REPORT NUMBER
                              Minerals Management Service                                                                                                    OCS Study MMS 99-0054
                              Gulf of Mexico OCS Region
                              1201 Elmwood Park Blvd
                              New Orleans LA 70123-2394
                           11. SUPPLEMENTARY NOTES






                           12a. DISTRIBUTION /AVAILABILITY STATEMENT                                                                                         12b. DISTRIBUTION CODE


                              Unlimited





                           13. ABSTRACT (Maximum 200 words)
                              This report was prepared under contract between the Minerals-Management Service and
                              the Texas'A&M Research Foundation as part of the Chemical Oceanography and Hydrography
                              Study of the Northeastern Gulf of Mexico Physical Oceanography Program. It covers the
                              year July 1998 - June 1999. Selected preliminary results are presented from the first
                              four cruises in Nov 1997, May 1998, July/August 1998, and November 1998. Data col-
                              lected included Continuous profiles of salinity, -temperature, pressure, fluorescence,
                              light transmission, and downwelling irradiance. _Water samples were  analyzed for nu-
                              trients, dissolved oxygen, salinity, particulate matter, particulate organic carbon,
                              and phytoplankton pigments. Each cruise collected continuous ADCP along-track sur-
                              veys. Historical and concurrent data from other programs also were collected.








                           14. SUBJECT TERMS                                                                                                                              15. NUMBER OF PAGES
                                                                                                                                                                               123

                                                                                                                                                                          16. PRICE CODE
                         






















































                           17. SECURITY CLASSIFICATION                   18. SECURITY CLASSIFICATION                     19. SECURITY CLASSIFICATION                     20. LIMITATION OF ABSTRACT
                                OF REPORT                                      OF THIS PAGE                                     OF ABSTRACT
                              unclassified                                    unclassified                                      unclassified                                  unlimited
                        NSN 7540-01-280-5500                                                                                                                         Standard Form            8 (Rev 2-89)
                                                                                                                                                                     
 


























                                                        US Department of mmerce
                                                  NOAA CoaiW Services Ccocenter LibrarY
                                                          2234 South Hobson Avenue
                                                           Charleston, SC 29405-2413



                f_14T op
                                The Department of the Interior Mission

                                As the Nation's principal conservation agency, the Department of the Interior has responsibility for
                                most of our nationally owned public lands and natural resources. This includes fostering sound use
                                of our land and water resources; protecting our fish, wildlife, and biological diversity; preserving the
                                environmental and cultural values of our national parks and historical places; and providing for the
                 C H 3 its      enjoyment of life through outdoor recreation. The Department assesses our energy and mineral
                                resources and works to ensure that their development is in the best interests of all our people by
                                encouraging stewardship and citizen participation in their care. The Department also has a major
                                responsibility for American Indian reservation communities and for people who live in island territories
                                under U.S. administration.

                                The Minerals Management Service Mission

                                As a bureau of the Department of the Interior, the Minerals Management Service's (MMS) primary
                                responsibilities are to manage the mineral resources located on the Nation's Outer Continental Shelf
                                (OCS), collect revenue from the Federal OCS and onshore Federal and Indian lands, and distribute
                                those revenues.

                                Moreover, in working to meet its responsibilities, the Offshore Minerals Management Program
                                administers the OCS competitive leasing program and oversees the safe and environmentally sound
                                exploration and production of our Nation's offshore natural gas, oil and other mineral resources. The
                                MMS Royalty Management Program meets its responsibilities by ensuring the efficient, timely and
                                accurate collection and disbursement of revenue from mineral leasing and production due to Indian
                                tribes and allottees, States and the U.S. Treasury.

                                The MMS strives to fulfill its responsibilities through the general guiding principles of: (1) being
                                responsive to the public's concerns and interests by maintaining a dialogue with all potentially affected
                                parties and (2) carrying out its programs with an emphasis on working to enhance the quality of life for
                                all Americans by lending MMS assistance and expertise to economic development and environmental
                                protection.








                                                                                                             ]-1 3













                                                       Minerals Management.Service
                                                          Gulf of Mexico OCS Region









                                                                    U.S. Deportment of the RMIM





                                                     Managing America's offshore energy
                                                                          resources


                                                           Protecting America's coastal
                                                              and marine environments