Detection and characterization of submesoscale eddies off the southwestern coast of Puerto Rico

Ubiquitous submesoscale eddies (SE) have been reported to play a major role in upper ocean stirring, mixing and littoral water circulation. Remotely sensed ocean color imagery provided the first views of coherent submesoscale features all around the Puerto Rico coast. Operational numerical models for the region such as NCOM AMSEAS (3km and 3-hours) and global HYCOM (9km and 3-hours) are not able to resolve these. Deployments of High-Frequency Radars (HFRs) off the southwest coast of Puerto Rico now make possible hourly surface current observations which allow detection and characterization of the two dimensional structure of these submesoscale features. Numerical detection of these features has been achieved by the implementation of a vector geometry identification scheme on the HFR data, which has recently led to an exploratory analysis of a cyclonic persistent SE structure. The detected cyclone had a strong well-defined inner core structure coherency and a 13.86km radius,

SE was manually confirmed using USF’s Alternative Floating Algae Index satellite imagery (1km and daily), which showed the detected eddy center location had an offset of <8km from the real eddy center which was estimated thanks to a patch of floating algae, presumably Sargassum sp., entrained in its center. NCOM AMSEAS or HYCOM did not resolve the observed SE. Further work will focus on the 3D description of these SEs. HFR vector fields, XBT’s, CTD’s and Glider profile data will be used to characterize the horizontal and vertical extent of the dynamics involved with these SEs.