Precision of regional mean sea level and continental ice sheet topography as determined by satellite altimetry

Abstract Altimeter data provide a useful complement to tide gages for monitoring the mean sea level or the continental ice topography. We discuss here how these signals can be separated from measurement errors and from other ocean signals. With existing data, the formal error which can be achieved is of the order of 5 cm rms, for a regional, yearly averaged, mean sea surface, and 50 cm rms for continental ice. These errors are likely to improve further as better orbits and corrections are made available. This suggests that secular trends will be observable when 20 years of coherent data (from SEASAT to the Polar Platforms) will be assembled.