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ERS-1 Preliminary Marine Geoid

Using the first four months of the first 168-day ERS-1 repeat cycle, a Preliminary Marine Geoid (or Mean Sea Surface) has been computed at NNG. The resolution of this model is 0.3 deg and its accuracy is better than 10 cm. It has been validated using TOPEX and Poseidon data. Altimeter residuals drop to below 14 cm using this model. Previously used OSU-91A geoid yielded 20 cm residuals.

The radius of the ellipsoid associated to this geoid is 6378.1367 km (6378.1363 km for OSU-91A), determined as the best fitting values to the three altimeter biases (ERS-1, TOPEX and Poseidon). A jump of 40 cm can be observed in the ERS-1 altimeter bias when changing from OSU-91A to this new marine geoid.

This map shows a world region with the differences between the Preliminary Marine Geoid and the OSU-91A geoid.