Geoid Determination Over Basin-Wide Scales Using a Combination of Satellite Tracking, Surface Gravity and Altimeter Observations
A spherical harmonic model of the Earth’s gravitational field has been developed using tracking data of 31 satellites, surface gravimetry, and satellite radar altimetry. The model is complete to degree and order 50 and provides a simultaneous recovery for invariant and tidally induced gravitational effects. The ocean tidal model consists of 600 background tidal terms with 90 coefficients being adjusted. The altimeter data are utilized as tracking observations of the ocean surface and provide for a simultaneous recovery of a model describing the stationary sea surface topography complete to degree and order 10 in spherical harmonics. Comparisons between satellite-only models and those obtained with the addition of altimetry/gravimetry find an improvement in geoid representation of more than a factor of two, extending even to the model’s longest wavelengths. The stability of the geoid recovery has been assessed using subset solutions. For wavelengths of 2000 km or longer, the combination model provides geoid definition of 6 cm rms accuracy.
KeywordsAltimeter Data Satellite Tracking Gravitational Model Geoid Determination Ocean Tidal Model
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