Tidal Models in a New Era of Satellite Gravimetry

Abstract

The high precision gravity measurements lo be made by recently launched (and recently approved) satellites place new demands on models of Earth, atmospheric, and oceanic tides. The latter is the most problematic. The ocean tides induce variations in the Earth’s geoid by amounis I hat far exceed the new satellite sensitivities, and tidal models must be used to correct for this. Two methods are used here lo determine the standard errors in current ocean tide models. Al long wavelengths these errors exceed the sensitivity of the GRACE mission. Tidal errors will not prevent the new satellite missions from improving our knowledge of the geopotential by orders of magnitude, but the errors may well contaminate GRACE estimates of temporal variations in gravity. Solar tides are especially problematic because of their long alias periods. The satellite data may be used lo improve tidal models once a sufficiently long time series is obtained. Improvements in the long-wavelength components of lunar tides are especially promising.