Augmentation of AUSGeoid98 with Grace satellite gravity data

The AUSGeoid98 gravimetric quasigeoid model of Australia is augmented in the medium‐ and long‐wavelength bands by removing its EGM96 basis and replacing this with GGM02C and EIGEN‐GL04C, whose long wavelengths are derived from Gravity Recovery And Climate Experiment (GRACE) satellite gravimetry No significant improvement over AUSGeoid98 is seen: agreements with GPS‐levelling change from ±28 cm to ±27 cm (acknowledging distortions in the levelling); agreements with astrogeodetic vertical deflections do not change, remaining at about ± 1 arc‐second. While this remove‐replace approach is not theoretically exact, it is likely that errors in the terrestrial gravity data are contaminating these combined GRACE solutions in the medium wavelengths over Australia.

Keywords:

• Geodesy
• quasigeoid modelling
• GRACE
• GPS‐levelling
• vertical deflections
• Australia