SATELLITE ALTIMETER DERIVED GEOSTROPHIC CURRENTS IN THE WESTERN TROPICAL PACIFIC DURING 1992-1993 AND THEIR VALIDATION WITH DRIFTING BUOY TRAJECTORIES

TOPEX/POSEIDON satellite altimeter measurements from the western tropi cal Pacific (15 degrees S-20 degrees N, 125 degrees E-165 degrees W) a re used to make monthly sea surface topography maps for the period Oct ober 1992 to October 1993. The altimeter data were processed using sta ndard corrections to estimate along-track sea surface height anomalies which were interpolated to monthly 1/10 degrees resolution maps. To c onvert these surface height anomalies to absolute sea surface height, a 0/1000-dbar mean seasonal dynamic height climatology was computed fr om the same input data used by Levitus (1982) to compute his dynamic h eight climatology, with less spatial smoothing. By adding the appropri ate monthly altimeter heights to these seasonal means, we produce 12 a pproximately monthly sea surface topography maps from 36 cycles of alt imeter data. The corresponding monthly geostrophic surface currents we re compared with the tracks of nearly coincident satellite-tracked dri fting buoys and were found to agree well in most cases. The velocity c omponents (zonal and meridional) were plotted separately with respect to the velocities estimated from the buoy positions, and correlations of these two data sets are very high. The seasonal variability of the surface geostrophic currents in this region is depicted by the monthly maps of sea surface height.