The mean sea surface has been computed using a 7-year TOPEX/POSEIDON mean profile, a 5-year ERS-1/2 mean profile, a 2-Year GEOSAT mean profile and the 2 168-day non repeat cycle data of the ERS-1 geodetic phase. All these data have been preprocessed in order to be:
a) more homogeneous, and referenced to the 7-year T/P mean profile,
b) less contaminated by the ocean topography variable signal (the mean ocean topography signal contained in the surface is thus corresponding the mean sea level during the period 1993-1999).
The surface have been estimated on a 1/30 (2 minutes) of a degree grid using a local inverse method, which also provides an estimation error field. The files corresponding to these 2 fields are described below.

This mean sea surface contains:
- Over ocean, the mean geoid plus the mean ocean dynamic topography (1993-1999)
- Over land, the EGS96 mean geoid
- In coastal areas (between ocean and land)... A smooth extrapolation/relaxation of the ocean values (geoid+mean dynamic topography) toward the EGM96 geoid