RESOLUTION OF THE SCRIPPS NOAA MARINE GRAVITY-FIELD FROM SATELLITE ALTIMETRY/

The July 1995 declassification of the entire Geosat GM satellite altim eter data set enabled a joint Scripps/NOAA effort to compute a new (ve rsion 7.2) marine gravity field on a 2-minute grid. This gravity field covers the world's oceans between 72 degrees N and 72 degrees S, and is derived from a combination of ERS-1 and Geosat GM and ERM data. An earlier NOAA Geosat-only gravity field solution was confined to the so uthern latitudes because the 1992 declassification was limited to GM d ata south of 30 degrees S. A simple coherence analysis between accurat ely-navigated ship gravity profiles and comparable gravity profiles ob tained from the gravity grids reveals that the Scripps/NOAA gravity fi eld is coherent with ship gravity down to similar to greater than or e qual to 23-30 km. This slight increase in resolution over the previous NOAA Geosat-only gravity field (short-wavelength resolution of simila r to 26-30 km) implies that the increased spatial coverage provided by the ERS-1 altimeter, when combined with Geosat, improves the solution . Coherence analyses between satellite gravity and ship topography, an d ship gravity and ship topography, show that even shorter wavelength gravity anomalies (similar to 13 km) are present in sea-surface measur ements made by ship. Even so, the Scripps/NOAA marine gravity field do es an excellent job of resolving most of the short-wavelength gravity anomalies covering the world's oceans.