Comparison of Satellite Altimetric Gravity and Ship-Borne Gravity — Offshore Western Australia

Abstract

Since 2010 several new satellite altimetry missions have commenced delivering altimetry-derived gravity data with a global offshore coverage and with a quality in many regions nearing that of ship-borne gravity observations. This is resulting in greatly improved global offshore high resolution gravity fields.

The DTU13 and Sandwell and Smith’s v23.1 grids of altimetric gravity anomalies from offshore Western Australia are compared with ship-track gravity anomalies computed from the Geoscience Australia marine gravity database. The standard deviation of the difference between the ship-borne gravity data and the satellite altimetric gravity data is 3.1mGal for the DTU13 data and 3.3 mGal for Sandwell and Smith’s v23.1 grid. In water depths less than 20m we observed significant differences between ship-borne gravity and altimetric gravity. Over the sampled wavelengths, the DTU13 altimetric gravity data appears to have the best resemblance to the reference marine gravity data, exhibiting the overall least difference amplitude over most wavelengths.