Deep Ocean Interactions with the West Florida Shelf: the Role of the “Pressure Point” on Both Across Shelf Transport and the Penetration of the Loop Current into the Gulf of Mexico

Yonggang Liu and Robert H Weisberg, University of South Florida, College of Marine Science, St. Petersburg, FL, United States
The southwest portion of the west Florida shelf (WFS) is a region of convergent isobaths as these must wrap around the Dry Tortugas, the westernmost islet of the Florida Keys chain. When the Gulf of Mexico Loop Current (LC) contacts the WFS slope at this “pressure point” region, it sets the entire shelf in an upwelling favorable motion. Under prolonged pressure point contacts the associated upwelling may bring new water of upper slope origin and material properties onto and across the shelf, with important ecological consequences. Such LC/shelf interactions, in turn, also affect the LC evolution by anchoring the LC in its direct inflow-outflow path configuration. Farther northward penetration into the Gulf of Mexico occurs when such anchoring is released. Both observations and numerical circulation modeling show how harmful algal blooms and reef fish recruitment are affected by the pressure point, and satellite altimetry analyses using machine learning (Self-Organizing Map) helped facilitate these discoveries.