[M-IS20] Global climate change driven by the Southern Ocean and the Antarctic Ice Sheet

[MIS20-P09] Determination of long-term mass variation of the Antarctic ice sheet using satellite gravimetry and satellite altimetry data

*Keiko Yamamoto¹, Jun'ichi Okuno², Koichiro Doi², Yoichi Fukuda² (1.National Astronomical Observatory of Japan, 2.National Institute of Polar Research)

Keywords:Antarctic ice sheet variation, Satellite gravimetry, Satellite altimetry

The accuracy and precision of the Antarctic ice sheet mass balance estimation has improved significantly with the recent development of satellite geodesy techniques. In particular, the use of satellite gravity mission data, such as GRACE and GRACE-FO data, is one of the effective means to estimate the temporal variation of a large-scale ice sheet as a change in mass. However, the dedicated gravity satellite observes the sum of the mass changes in the vertical direction. In Antarctica, in addition to the ice sheet mass change, the effect of mass redistribution inside the solid earth by Glacial Isostatic Adjustment (GIA) is also significant. To obtain the mass variation of the ice sheet, the effect of GIA must be subtracted. However, currently released several GIA models have large uncertainties, and as a result, the estimated ice sheet mass change also has large uncertainty. Using satellite altimetry data, which measures height change over time on the ice sheet surface, in addition to gravity measurement satellite data, is one way to overcome this problem. In principle, the observation equation of the mass change and the altitude change at each grid point are established from the temporally varying mass and surface altitude data, and it is possible to separate the ice sheet variation and GIA signals by solving the equation with least squares method in the time direction. In this study, we used about-20-year satellite gravimetry and satellite altimetry data derived from multiple satellites, i.e., GRACE and GRACE-FO, ICESat, ICESat-2, Envisat and Cryosat2, for the separation of the ice sheet mass variation and the GIA mass change. In the presentation, we will discuss long-term mass variations of the Antarctic ice sheet using the obtained ice sheet mass changes. We also discuss the obtained spatial patterns of GIA mass change.