Collapse of the peripheral bulge around Antarctica inferred from the satellite gravity data and GIA modeling

Abstract:

The loss of the Antarctic ice mass is accelerating due to recent global warming. Changes in Antarctic ice mass have been observed as the gravity change by GRACE (Gravity Recovery and Climate Experiment) satellites. However, the gravity signal includes both the components of the ice mass change and the solid Earth response to the surface mass change (Glacial Isostatic Adjustment, GIA). Namely, to constrain the ice mass change by gravity observation, the viscosity structure of the mantle and the deglaciation history of the ice sheets with sufficient accuracy is required. In this study, we focus on the changes in the gravity field in the peripheral bulge around the Antarctic ice sheet, which is the area that the GIA signals are relatively large in the coastal region around Antarctica. At present, since the crustal subsidence of the peripheral bulge should be proceeding, the gravity field may be changing with the crustal deformations; however, no such observation has been reported. Here we examine changes in the gravity field caused by the subsidence of the peripheral bulge using the GIA modeling with high spatiotemporal resolution. We also clarify the dependence of the viscosity and deglaciation history on the gravity change in the peripheral bulge around Antarctica. In this presentation, we intend to discuss the verification of whether the deformation of the peripheral bulge can be detected and constrain the GIA model parameters using the GRACE data.