Submesoscale and mesoscale eddies in the Florida Straits: Observations from satellite ocean color measurements

Yingjun Zhang1, Chuanmin Hu1, Yonggang Liu1, Robert H Weisberg1 and Vassiliki Kourafalou2, (1)University of South Florida, College of Marine Science, St. Petersburg, FL, United States, (2)Univ of Miami, Miami, FL, United States
Despite their well-recognized importance in driving ocean physics and biology, submesoscale (diameter < Rossby radius of deformation) eddies have been extremely difficult to observe due to technical difficulties from both field and remote platforms. Here, using modified algorithms and novel satellite ocean color data products (daily, 500-m spatial resolution, 2002-2018) which are generally immune to perturbations by sun glint, thin clouds, straylight, and sensor saturation hence have 3 - 5 times more valid data coverage (i.e., suitable for the purpose of studying submesoscale features) as compared to the standard NASA chlorophyll imagery, we address this challenge for the Florida Straits. Between 2002 and 2018, while mesoscale eddies (radius > 15 km) show strong seasonality with occurrence frequency decreasing from Lower Keys to Upper Keys, submesoscale eddies show less seasonality with high occurrence frequency restricted to 30-200m isobaths. The number of mesoscale eddies decreases exponentially in size, but submesoscale eddies show a normal distribution in size. These findings are significant in filling our knowledge gap in submesoscale eddies in this physically and ecologically important region as it encompasses world-renowned coral reefs, seagrasses, and fisheries.