Marine Gravity from Satellite Altimetry over Ocean and Sea Ice

Radar altimeter measurements of the marine geoid collected during the Seasat altimeter mission gave marine geodesists and geophysicists a hope of uncovering the details in the gravity field over all the ocean basins. However because of insufficient track density, it has taken 16 years for the full potential of the satellite altimeter method to be realized. The high density coverage obtained by ERS-1 during its geodetic mapping phase (4/94–3/95) prompted the US Navy to declassify all of the Geosat altimeter data (6/22/95). We are grateful to ESA for extending the ERS-1 mapping phase so that an equatorial ground-track spacing of 8 km could be completed. The combination of these two high-density data sets will provide the first detailed view of all the ocean basins. Considering the sparse shipboard coverage of many ocean areas [Smith, 1993], these new altimeter data are arguably the most important marine geology and geophysics data set collected over the past decade.