The ice sheet height changes and mass variations in Antarctica by using ICESat and GRACE data

Abstract

The Gravity Recovery and Climate Experiment (GRACE) satellite mission has provided the monthly earth's gravity field models since August 2002, from which the mass variations in Antarctica can be estimated. Because of the very low-degree spherical harmonic coefficients, especially the degree-2 zonal term J2 are not well determined by GRACE, more attention should be paid on the effects of J2 when the earth's mass variations are derived from spherical harmonic coefficients. To see the differences more clearly, wavelet transformation is applied to the J2 time series derived from GRACE measurements by different agencies, such as Centre National d’Études Spatiales/Groupe de Recher de Deodesie Spatiale, GeoForschungsZentrum Potsdam, University of Texas Center for Space Research and that from satellite laser ranging observations. Periodic signals can be seen from the wavelet spectra. A Gaussian smoothing with a radius of 300 km is used in the gravity model-based mass rate estimation. Meanwhile, NASA's Ice, Cloud, and land Elevation Satellite (ICESat) has provided repeated laser altimeter data, and the ice sheet height changes are estimated by using crossover analysis. The mass rates estimated from GRACE are compared to the ice sheet height changes from ICESat. The mass rate in Amundsen Sea Embayment is estimated up to −8 cm/yr from GRACE, while the ice sheet height changes observed from ICESat is up to −32 cm over more than 3 years, this shows the comparable results in this region.