Dynamic Structure of the Gulf of Tehuantepec in Coupled Ocean-Atmosphere Nested Modeling and Observations

A strong offshore wind event during the Gulf of Tehuantepec EXperiment (GOTEX) in February 2004 is simulated using the Coupled Ocean/Atmosphere Mesoscale Prediction System (COAMPS®*) with three nested grids in the atmospheric component and two nested grids in the oceanic component. The ocean component includes the Navy Coupled Ocean Data Assimilation (NCODA) and the Navy Coastal Ocean Model (NCOM). Satellite observations of sea-surface temperature (SST), sea-surface height, and in situ surface and sub-surface observations of temperature and salinity obtained from the Global Ocean Data Assimilation Experiment (GODAE) server are assimilated. The results are compared and validated with QuikSCAT wind speed, TMI SST, and observations from aircraft and airborne expendable bathythermographs (AXBTs) during the GOTEX. The study is focused on the interaction of an offshore wind jet with an existing anticyclonic eddy in the ocean. The characteristics of the offshore wind forcing and related vertical mixing and upwelling in the ocean are examined to indentify their important roles in enhancing the anticyclonic and cyclonic eddies in the Gulf. The research also presents the results of eddy propagation after the offshore wind event. The differences between the inner and outer nests of the ocean model due to the increased resolution of the wind event and the ocean response are discussed as well.