Anassessment of GIA solutions based on high-precision GNSS velocity field for Antarctica

Abstract. Past mass loads, especially LGM (Last Glacial Maximum), may cause the viscoelastic response of the Earth, this phenomenon is the so-called glacial isostatic adjustment (GIA). GIA not only includes the horizontal and vertical motions of the crust but also the shape, the gravity field and rotation axis of the earth. Due to the uncertainties in the ice loading history and the mantle viscosity, modeling GIA will be difficult and challenging in Antarctica. The GPS velocity field provides an effective method to constrain the GIA vertical velocity; however, to obtain the high-precision GPS velocity field, we must consider the effects of common mode error(CME) and the choice of optimal noise model (ONM). We used independent component analysis(ICA) to remove the CME recorded at 79 GPS stations in Antarctica and determined the ONM of GPS time series based on the Akaike information criterion (AIC). Then, the high-precision GPS velocity field is obtained; we used the high-precision GPS velocity field to assess the application of GIA models in Antarctica. The results show that the maximal GPS velocity variation is up to 1.15 mm yr⁻¹, and the mean variation is 0.18 mm yr⁻¹. We find systematic underestimations of all GIA model velocities in the Amundsen Sea area (ASE). In the north Antarctic Peninsula (NAP), the vertical velocities are underestimated by 6 GIA models but not the WANG model. Because the upper mantle viscosities in the NAP are lower than those in the south Antarctic Peninsula (SAP),the GPS vertical velocities in NAP regions are larger than SAP regions. In the Filscher-Ronne Ice Shelves (FRIS), the observed GPS velocity and predicted GIA model velocity are consistent. In East Antarctica (EA), the vertical motion is nonsignificant, and the GIA and ice loading have a small impact in this area.