Feasibility Study for a Novel Instrumental Technique to Characterize Subsurface Currents and Hydrography Within the Alaska Ocs. Final Report

Publication Title: Feasibility Study for a Novel Instrumental Technique to Characterize Subsurface Currents and Hydrography Within the Alaska Ocs. Final Report

Subject: Physical Oceanography
Beaufort Shelf; Lower Cook Inlet; Shelikof Strait; ocean currents

CSE Reference: McMonigal K, Beight J (University of Alaska Fairbanks, Fairbanks, Alaska). 2025. Feasibility study for a novel instrumental technique to characterize subsurface currents and hydrography within the Alaska OCS. Final Report. Anchorage (AK): U.S. Department of the Interior, Bureau of Ocean Energy Management. 53 p. Award No.: M23AC00011. Report No.: OCS Study BOEM 2025-018. URL: https://espis.boem.gov/final%20reports/BOEM_2025-018.pdf

Abstract: Ocean currents have impacts on ecosystems, through the transport of nutrients and larvae, and on human societies through dispersal of pollutants. Quantifying ocean currents in the rapidly changing Arctic and sub Arctic is important for fisheries, communities, and transportation. Surface ocean currents can be relatively easily observed from satellites and high frequency radar. However, subsurface currents require mooring deployments to resolve. This can sometimes require multiple instruments, and can be difficult in seasonally ice covered regions. In this project, we assessed the feasibility using a new measurement technique, called “Current and Pressure Recording Echosounders” (CPIES) to estimate subsurface ocean currents on the Beaufort Shelf and Slope, in Lower Cook Inlet, and in Shelikof Strait using output from the ROMS model. We find that the CPIES measurement technique is theoretically feasible based on signal-to-nose ratios. We also find that CPIES can adequately estimate subsurface temperature profiles in the model output. However, large errors in salinity estimates lead to biases in the estimated ocean current velocity. Of the three locations investigated, the lowest errors are in Shelikof Strait. A future test deployment of a CPIES side by side with an acoustic Doppler current profiler would refine our feasibility estimates, which may be limited by model errors.