Detailed Gravity Anomalies and Sea Surface Heights Derived from Geos-3/Sesat Altimeter Data.

Gravity anomalies and sea surface heights have been computed on a 0.125 deg grid in the ocean areas from a combined Geos-3Seasat altimeter data set. The basic procedure used least squares collocation estimation where model covariance models were tailored to individual areas through altimeter residual variance scaling. Preliminary tests led to production prediction procedures using a reference model defined by a set of potential coefficients complete to degree 180. Comparisons of the predicted anomalies with ship derived values showed agreements varying from or - 9 to or - 30 mgals. No corrections to the altimeter implied sea surface heights were made for sea surface topography effects. The maximum anomaly predicted was 396 mgals near Hawaii and the most negative anomaly was -361 mgals over the Puerto Rican Trench. The 0.125 data set has been used to display the results using color plots, contour maps, and perspective views. The gridded data was used to compute 1 deg x 1 deg and 0.5 x 0.5 deg mean values. 1 deg mean anomalies were compared to terrestrial data where a difference of or - 7 mgals was found in comparing 10139 values.