A Stokesian Approach for the Comparative Analysis of Satellite Gravity Models and Terrestrial Gravity Data

A Stokesian approach is formulated to update the geoid model for a specific spherical harmonic band by spectrally combining a GOCE-based satellite global geopotential model with terrestrial gravity data. A simulation test shows that the GOCE-based model can be combined into a geoid solution with an accuracy better than 3mm for the band between degrees 90 and 180. A comparison of the GOCE-based model GOCO03S and the Canadian terrestrial gravity data for the spherical harmonic band between degrees 90 and 180 shows that the geoid update by GOCO03S reaches 1.6 cm in RMS in the Yukon Territory, 1.8 cm in northern British Columbia, and 1.6cm in the Maritimes. This may suggest a slight improvement of the GOCE model over the Canadian gravity data considering the standard deviation of 1.0 cm given by GOCO03S. However the analysis indicates comparable accuracy between the terrestrial gravity data and GOCE models for the rest of Canada where topography is relatively flat. The comparisons at the GPS-levelling points suggest that GOCE has improved our existing knowledge of the Earth's gravity field for wavelength components longer than 200km over the Yukon Territory, northern British Columbia, the Maritimes, and Newfoundland.