The effects of atmospheric and thermohaline variability on the validation of the GEOSAT altimeter oceanographic signal between Scotland and Iceland

Abstract

Atmospheric and oceanographic profiles from the area between Scotland and Iceland are analysed in

order to predict the magnitudes of the errors they can induce in satellite altimeter measurements of

sea-surface topography. This is the area where the second phase of the COMPASS project will take place in early 1988, and the aim is to provide absolute calibration data for the GEOSAT altimeter by using coastal land-based active microwave transponders. While most of the variability in the seasurface

topography can be ascribed to variations in the temperature profile, the spatial changes in the

temperature-salinity relationship are such that errors in the sea-surface topography predicted from

measured temperature profiles can not be neglected. This means that the validation of the altimeter

oceanographic signal can not be done in this area by using only the more readily-available temperature profiles from expendable probes. The atmospheric variability characteristic of this area

can induce errors in the altimeter range measurement comparable to the oceanographic signal, and careful corrections are necessary. These will have to faithfully reflect the changes in atmospheric properties along the COMPASS arc.