Effects of glacial isostatic adjustment on the estimate of ice mass balance over Antarctica and the uncertainties

The effects of glacial isostatic adjustment (GIA) on monitoring ice mass balance over Antarctica are investigated using our newly-released GIA model ICE-4G+RF3L20 (beta = 0.4) and the uncertainties are evaluated by considering the effects of differences in ice load models and reference mantle viscosities. The results and the comparison with those from GRACE time-varying gravity fields and satellite altimetry data are shown as follows. It is found that the GIA has strong effects on monitoring the changes of equivalent water height (EWH) from GRACE gravity data, significant GIA effects occur at Ross Ice Shelf, Kamb Ice Stream, Ronne Ice Shelf and Antarctic Peninsula with a maximal magnitude of similar to 29.8 mm/a at Kamb Ice Stream. For the whole Antarctica, the effect of GIA on total ice mass balance is 134 +/- 28 Gt/a. The differences in ice models account for 88.4% of the variances of uncertainties while the differences in viscosity models contribute 11.6%. In some typical regions, the changes of EWH monitored by GRACE data are given before and after GIA corrections. These are similar to 32.8 mm/a and similar to 6.3 mm/a for Kamb Ice Stream, similar to-95.3 mm/a and similar to-102.5 mm/a for Amundsen Sea Embayment, similar to 13.6 mm/a and similar to 8.1 mm/a for Enderby Land. The total ice mass change of the whole Antarctica is found to be -82 +/- 29 Gt/a after GIA corrections which is quite close to that estimated from satellite altimetry data. Furthermore, the effects of GIA on the ice height changes observed from ICESat are less than 8%. The results related to our new GIA model in this paper can be utilized to precisely monitor the present ice mass balance in Antarctica from space geodetic techniques.