Comparison of Several Filters in the Rates of Antarctic Ice Sheet Mass Change Based on GRACE RL05 Data

Time-variable series of earth gravity model are obtained by means of GRACE, which can be continuously monitor variations of the mass in or on the surface of the Antarctic ice sheet in middle and large scales. Gravity solutions of GRACE RL05 from January 2003 to July 2013 released by UTCSR are used in this paper. Several filters, such as isotropic Gauss, non-isotropic, Fan, Wiener and de-correlated filter, were compared in the inversion of the Antarctic ice sheet mass change rates. Through analysis and comparison, the following conclusions are obtained: (1) The signal and noise function of Wiener were calculated by 121 months gravity model and the result was very close to that of the Gaussian smoothing radius of 300 km, and that is mass change can be completely extracted by using the 300km radius of filtering; (2) Increasing the radius of the filter is an effective way to improve the accuracy of the results, so the propositional radius of filtering in the Antarctic area can be 500km; With the same filter radius, the rates of mass changed are basically consistent for different methods; (3) De-correlated filter is more effective method in reducing the systematic errors of spherical harmonic coefficient. The conclusions as above help reconcile CRACE ice mass estimates obtained for different filter strategies.