CoAuthors

Clifford R. Merz (University of South Florida, USA); Robert H. Weisberg (University of South Florida, USA); Lynn K. Shay (University of Miami, USA); Scott Glenn (Rutgers University, United States); Michael Smith (University of South Florida, United States)

A long-range (4.9 MHz) Coastal Ocean Dynamics Applications Radar (CODAR) SeaSonde was deployed at Marathon, Florida (along the Florida Keys chain) in December 2019 to observe surface currents in the Straits of Florida. The High-Frequency Radar (HFR) radial current data provide an opportunity to compare with the surface geostrophic currents derived from the near real time Jason-3 along-track and gridded sea surface heights from satellite altimetry (AVISO+ products), and with surface currents from data assimilative Gulf of Mexico HYbrid Coordinate Ocean Model (HYCOM) in this area of complex ocean current dynamics. The HFR and the along-track altimetry-derived radial velocity components agree to within a root-mean-square difference (RMSD) of about 21 cm/s. The agreement with the gridded altimetry product varies within the HFR footprint, with a RMSD range of 16.2 – 61.2 cm/s and mean value of 34.1 cm/s when spatially averaged over the HFR domain. Lesser agreement is found with the HYCOM output, wherein the RMSD range is 15.2 – 82.3 cm/s and the mean value is 39.9 cm/s. The Largest RMSD values are generally within the Florida Current frontal regions where frequent mesoscale eddy activity occurs. These findings have important implications for users of both altimetry data products and data assimilative numerical ocean circulation models.