Assimilation of drifter and satellite data in a model of the Northeastern Gulf of Mexico

Drifter and satellite data are assimilated into a circulation model that hindcasts near-surface currents in the Northeastern Gulf of Mexico. Experiments without assimilation, and using assimilation of drifter, satellite sea-surface height (SSH) and sea-surface temperature (SST) data, in various combinations, were conducted. Currents derived from these experiments were used to compute drifter trajectories that were compared against observations. Surface geostropic current fields, calculated from satellite SSH, were also used to generate drifter paths. Assimilation that used a combination of drifter and satellite data reproduced the drifter trajectories with position errors ≈30-80km over a 10-day period. Comparisons of the modeled currents with moored observations on the West Florida shelf show improvement when data assimilation is used, because of better simulation of deepwater processes (primarily the loop current).