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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-1�99 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 �0.05 pLg-L-' or better in low chlorophyll, bio-optical 61 Type 11 environments and to � 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 �R 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 �R 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. 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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