SEA SURFACE CURRENT IN THE GULF OF THAILAND BASED ON NINETEEN YEARS ALTIMETRIC DATA AND GPS TRACKED DRIFTING BUOY

ABSTRACT: The advent of satellite altimetry in the last two decades has been much improved our understanding of mesoscale features of ocean circulation. Present study describes the seasonal variations of geostrophic current within the Gulf of Thailand using the seasonally averaged sea level anomaly (SLA) data from multi-mission satellite altimetry. Nineteen years of multi-mission satellite altimetry data from year 1993 to 2012 have been processed using Radar Altimeter Database System (RADS) and used to estimate the surface geostrophic current. In RADS data processing, the 2012 updated environmental and geophysical corrections were applied. Comparison of satellite estimated sea level anomaly with in-situ observations from two tide gauges station; Getting and Ko Lak have shown close similarity in the pattern of sea level variations and significant correlation coefficient. The surface geostrophic current anomaly is combined with the mean geostrophic (Mean Dynamic Ocean Topography model) to obtain the absolute geostrophic current. A basin-wide anti-cyclonic eddy exists throughout the year but it is weak during second inter-monsoon. Another anti-cyclonic eddy exist near the west cost of gulf throughout the year. In order to validate the surface current derived in this study, the obtained surface current patterns have been compared with drifting buoy trajectories. The pattern of estimated surface current is almost consistent with the Argos-tracked Drifting Buoy’s track and confirmed the basin wide anti-cyclonic eddy at the central Gulf of Thailand. 1