Acoustic Doppler Current Observations of Ocean Current Velocities from a SeaExplorer Glider
Water velocities computed from high-resolution observations collected by an acoustic Doppler current profiler (ADCP) mounted on an underwater, autonomous glider yield in-situ water current data with valuable applications. For example, ocean current velocities are significant for improving ocean circulation models, studying the impacts of hurricanes on oceans, predicting the spreading of harmful algal blooms and dead zones, and estimating transport of volume, heat, sediments, nutrients, and pollutants. There are two widely-accepted processing methods for obtaining water velocities from glider-ADCP observations; processing is customized to account for glider and sensor manufacturer differences and configuration options. This research involved implementing MathWorks® MATLAB code to compute water velocities for observations collected by a buoyancy-driven SeaExplorer glider equipped with an upward-facing, Nortek AD2CP-Glider sensor. The glider, SEA039, was acquired by the Department of Geological Sciences at The University of Texas at San Antonio (UTSA). Its two-week test mission dataset, collected in April 2018 in the Northwestern Mediterranean Sea, was utilized for this research. Water velocities obtained using the least-squares inversion method were compared to manufacturer-provided results for the same dataset processed using a shear algorithm. Results show encouraging correspondence between the two methods with opportunities for improvements in future work. Development of ADCP-processing code for UTSA's AD2CP-equipped SeaExplorer glider enables in-house processing of future SeaExplorer-observed water velocity data. This capability is essential to expand departmental research to include ocean sciences and to complement the research activities of UTSA's NASA Center for Advanced Measurements in Extreme Environments by incorporating new observational technologies and data science.