EVALUATION OF TOPEX AND BASIN-WIDE TROPICAL OCEAN AND GLOBAL ATMOSPHERE-TROPICAL ATMOSPHERE OCEAN SEA-SURFACE TOPOGRAPHIES AND DERIVED GEOSTROPHIC CURRENTS

Fields of TOPEX-derived sea level anomalies are validated against and compared with fields of Tropical Ocean and Global Atmosphere-Tropical Atmosphere Ocean (TOGA-TAO) dynamic height anomalies for the first 470 days of the TOPEX/POSEIDON mission. At periods longer than 35 days, T OPEX sea level anomalies compare extremely well with TOGA-TAO dynamic height anomalies throughout the whole basin, with a mean correlation o f 0.79 and mean rms differences of 2.6 cm. Zonal geostrophic current a nomalies are then derived from both data sets and validated against in situ current meter measurements at the equator. TOPEX-derived geostro phic current anomalies at the equator are in good agreement with in si tu currents at 0 degrees-165 degrees E, 0 degrees-170 degrees W, 0 deg rees-140 degrees W, and 0 degrees-170 degrees W. TOGA-TAO-derived curr ent anomalies compare well with in situ currents at 0 degrees-110 degr ees W, 0 degrees-140 degrees W, and 0 degrees-170 degrees W, but poor comparisons at 0 degrees-165 degrees E are thought to be linked to the absence of instantaneous salinity measurements in the dynamic height calculation. Despite localized discrepancies, basin-wide TOGA-TAO geos trophic currents compare reasonably well with TOPEX-derived geostrophi c currents. The discrepancies in the comparison between TOPEX and TAO are shown to be mostly associated with gaps in TOGA-TAO space-time sam pling and subsequent gridding procedures.