Detecting Ocean Currents from Satellite Altimetry, Satellite Gravity and Ocean Data

Abstract

With the preparation and launch of the high accuracy geodetic missions CHAMP, GRACE and GOCE, the geoid models have been improved greatly. This gives us a good chance to combine a high precision sea surface height with improved geoids to estimate the dynamic ocean topography (DOT) and associated surface currents accurately. Combining the geoid model (EIGEN-CG01C) from CHAMP and GRACE missions with the time-averaged sea surface model KMS04, we calculate a new high accurate mean DOT, and then compare it with DOT derived from ocean hydrological data. When taking 3km as the reference depth datum, the correlation coefficient is larger than 0.9 and the discrepancy of mean values is very small between the DOT derived from altimetry/geoid and that from WOA01 salinity and temperature data. The surface geostrophic currents from the altimetry/geoid derived DOT map are very close to those from WOA01 derived DOT map. This independent knowledge of surface currents from the altimetry/geoid derived DOT is used in combination with the salinity and temperature data from NOAA’s WOA01 to retrieve the ocean currents as a function of depth. At 2000db, comparisons of the retrieved velocities of the deep geostrophic currents with the WOCE current meter observation show that the spread of velocity deviation is approximately normal distribution, while the spread of velocity deviation is ruleless. The reasons caused these discrepancies need further analysis.