Sea surface topography from a combination of gradiometry and precise satellite altimetry

Abstract

The determination of sea surface topography requires two types of measurements: one to obtain the mean sea surface, the other to obtain the geoid. While precise altimetry can be used for the first purpose, gradiometry seems at present to be the only efficient method to resolve the short wavelengths of the geoid beyond the mean sea surface approximation. The potential of this new technique for sea surface topography determination is treated in this paper. A brief description of the different gradiometer prototypes and proposals leads to a discussion of the spectral characteristics of the measured second‐order gradients. Special emphasis is given to the attenuation of the anomalous gravitational spectrum with height and the consequences this has for recovering those frequencies that are important for geoid determination. Results indicate that a resolution of the geoid below the 10‐cm level can be achieved by combining airborne gradiometry with a high order reference field, which could be obtained by either satellite‐to‐satellite tracking or satellite gradiometry.