Numerical Study of the Upper Ocean Response of the Western Caribbean Sea to Hurricane Mitch

Hurricane Mitch in October 1998 was one of the most disastrous storms in history to strike the central American countries. The impact of this hurricane on the upper ocean of the western Caribbean Sea (WCS) is investigated using a nested-grid ocean circulation modeling system. The nested-grid system has three subcomponents: a coarse-resolution outer model (~19 km) covering the WCS (72W-90W, 8N-24N), an intermediate-resolution middle model (~6 km) covering the Mesoamerican Barrier Reef System (84W-89W, 15.5N-20N), and a fine-resolution inner model (~2 km) covering the north coast of Honduras and the Bay Islands (85W-88W, 15.6N-17N). The newly developed two-way nesting technique based on the semi-prognostic method is used in this study. The nested-grid system is forced by 6 hourly NCEP/NCAR winds for the first 294 days prior to the arrival of the hurricane in the WCS, and then by the combination of the NCEP/NCAR wind forcing and an idealized vortex associated with Mitch in the following 20 days. The system is also forced by the monthly mean sea surface heat and freshwater fluxes and buoyancy forcing associated with major river discharges and storm-induced precipitation in the WCS. The simulated upper-ocean circulation during Mitch is characterized by strong and divergent currents under the storm and intense near-inertial currents and sea surface temperature cooling behind the storm, both of which are more energetic on the right of the storm track. The nested-grid system also reproduces the buoyant estuarine plumes extending from the coast off Honduras as inferred from SeaWiFS satellite data and detected in field measurements at Gladden Spit in Belize shortly after the passage of Hurricane Mitch.