| Summary: | This study compares global geopotential models (GGMs) released between 1996 and 2002, including four that incorporate data from the CHAMP dedicated satellite gravimetry mission, with terrestrial gravity field-related data over Australia and New Zealand. The GGM-implied gravity anomalies are compared with point free-air gravity anomalies on land; geoid heights compared with discrete geometrical heights from co-located GPS and sprit-levelling data on the local vertical datums; and absolute (Pizzetti) deflections of the vertical at the geoid are compared with absolute (Helmert) vertical deflection estimates at the Earth’s surface. The results indicate that EIGEN-2, which uses purely CHAMP data, is currently the best satellite-only GGM over Australia and New Zealand (acknowledging the presence of long-wavelength errors in the “control” data), whereas the various combined high-degree GGMs are not statistically significantly different from one another over Australia and New Zealand. A hybrid GGM was created from EIGEN-2 to degree 32 and EGM96 from degree 33 to 360, where the cut off was selected using the global error degree variances of each. This GGM makes a very slight improvement on all others, and thus will probably be used in near-future Australian and New Zealand geoid models
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