The Seasat altimeter mean sea surface model

Gridding techniques are used to combine an 18-day set of Seasat altimeter data and two precisely-computed Seasat ephemerides, in order to arrive at global contour maps of the mean sea surface topography. The altimeter data have an rms agreement of 111 cm with the SS3 mean sea surface computed by means of the PGS-S3 ephemerides, and of 70 cm with the SS4 mean surface derived from the PGS-S4 ephemerides. While comparisons with the GEM 10B 1 x 1 deg gravimetric geoid have yielded rms differences of 2.8 m, those with a global mean sea surface derived from GEOS 3 altimeter data show rms differences of 1.3 m and 1.1 m for the cases of the SS3 and SS4 surfaces, respectively. An SS4 mean sea surface topograph is featured among the study findings presented. Further improvements in the representation of mean sea surface topography are expected with the development of more accurate gravity models for orbit computation.