CIRCULATION IN THE GULF OF MEXICO FROM GEOSAT ALTIMETRY DURING 1985-1986

Using altimetry data obtained from the Geosat Geodetic Mission (April 1985 to October 1986), low-frequency sea surface height (SSH) variations are investigated in the Gulf of Mexico. SSH time series are formed using the method of Fu and Chelton and are used to calculate surface geostrophic current vectors. Spatial patterns of SSH and current vector variations enable the tracking of two major rings shed from the Loop Current. The rings drifted southwestward across the gulf and into the western boundary region at an average speed of about 3.4 cm/s. The buildup of the Loop Current was monitored, as well as the appearance of an eddy of uncertain origin in the southwestern gulf. Verification of the Geosat results are provided with surface drifers, AVHRR imagery, and hydrography.