Abstract
Abstract. We present regional-scale mass balances for 25 drainage basins of the Antarctic Ice Sheet (AIS) from satellite observations of the Gravity and Climate Experiment (GRACE) for time period January 2003 to September 2012. Satellite gravimetry estimates of the AIS mass balance are strongly influenced by mass movement in the Earth interior caused by ice advance and retreat during the last glacial cycle. Here, we develop an improved glacial-isostatic adjustment (GIA) estimate for Antarctica using newly available GPS uplift rates, allowing us to more accurately separate GIA-induced trends in the GRACE gravity fields from those caused by current imbalances of the AIS. Our revised GIA estimate is considerably lower than previous predictions, yielding an estimate of apparent mass change of 53 ± 18 Gt yr−1. Therefore, our AIS mass balance of −114 ± 23 Gt yr−1 is less negative than previous GRACE estimates. The northern Antarctic Peninsula and the Amundsen Sea sector exhibit the largest mass loss (−26 ± 3 Gt yr−1 and −127 ± 7 Gt yr−1, respectively). In contrast, East Antarctica exhibits a slightly positive mass balance (26 ± 13 Gt yr−1), which is, however, mostly the consequence of compensating mass anomalies in Dronning Maud and Enderby Land (positive) and Wilkes and George V Land (negative) due to interannual accumulation variations. In total, 6% of the area constitutes about half the AIS imbalance, contributing 151 ± 7 Gt yr−1 (ca. 0.4 mm yr−1) to global mean sea-level change. Most of this imbalance is caused by ice-dynamic speed-up expected to prevail in the near future.
Highlights
The current mass balance of the Antarctic Ice Sheet (AIS), and its response to a changing global climate, is challenging to assess due to the spatio-temporal gaps in the meteorological and glaciological instrumental records
We have provided a revised glacial-isostatic adjustment (GIA) estimate for Antarctica, AGE1, based on numerical simulations and newly available GPS uplift rates, as well as Gravity and Climate Experiment (GRACE) trends beneath the Filchner-Ronne Ice Shelf
The residual misfit of surface deformation associated with AGE1b (GRACE and GPS) and measured GPS uplift rates in Antarctica is −0.1 mm yr−1, which represents an improvement with respect to the GIA prediction, for example, of Whitehouse et al (2012b) (−1.5 mm yr−1 mean bias at 46 GPS stations of W12a model, optimum Earth model)
Summary
The current mass balance of the Antarctic Ice Sheet (AIS), and its response to a changing global climate, is challenging to assess due to the spatio-temporal gaps in the meteorological and glaciological instrumental records. Due to the sparsity of constraints on the ice sheet evolution during the last glacial cycle, both in space and time, the ambiguity introduced by the poorly known mantle viscosity beneath Antarctica, and the complexity of the ice-dynamic processes involved, the reconstructions and associated GIA predictions substantially differ in their magnitude and spatial pattern, causing a large uncertainty in the mass balance estimates from GRACE All GRACE mass balance and acceleration values provided represent error-weighted means with 2-sigma uncertainties for the results based on the GRACE coefficients CSR RL05 and GFZ RL05 for the time period January 2003 to September 2012
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
