2006 Ocean Sciences Meeting SEACOOS Presentation - Real-Time Surface Velocity Mapping Using Wellen Radars in the Florida Straits

For the program on "Application of High-Frequency Radar Technology for Coastal Oceanographic Studies II," OS24B-04. As part of the ONR sponsored Southeast Atlantic Coastal Ocean Observing System, a multi-station Wellen Radar (WERA) system is providing near-real time surface velocities at ~1 km resolution over a range of 80 to 100 km in the Florida Straits. Since July 2004, these 16 MHz systems illuminate a large area of the Florida Straits, which is dominated by the highly variable Florida Current system. Given a 125 KHz bandwidth, surface radar backscatter data are acquired over 5000 grid points every 10 minutes for surface currents, waves and wind directions. WERA technology represents a proven experimental approach for long-term monitoring of surface processes for a spectrum of coastal ocean applications related to fisheries, coral reef ecosystems, tracking pollutants, search and rescue operations, and air-sea interactions. The Florida Current produces an environment of large horizontal shears and mean vorticities of 5-7f (where f is the local Coriolis parameter) associated with energetic, submesocale flow features. Submesoscale motions and their gradients along the Florida Current are well resolved with WERA as observed in January 05 during the passage of an atmospheric front. These smaller-scale surface current features, defined here as flow features with length scales less than the internal deformation radius ~30 km, were coherent over scales of 2 to 20 km along the eastern flank of the Florida Current. Unlike mesoscale features, which are elongated in the along-shelf direction, submesoscale processes tend to be more isotropic with considerable cross-shelf exchange where large gradients in properties occur due to the interactions between estuarine and shelf water with the warm subtropical water. Such interactions have importance on fisheries and coral reef ecosystems as well as pollutant dispersion and the transport of harmful algae blooms. Given the high shears over short time intervals associated with submesoscale variability, WERA resolves this shorter-time scale variability that will be useful in building coastal ocean models to resolve these processes. *L K Shay, T M Cook, B K Haus, J Martinez-Pedraja, H Peters, W E Johns, K Gurgel