| Summary: | Recent observations from satellite gravimetry (the Gravity Recovery and Climate Experiment (GRACE) mission) suggest an acceleration of ice mass loss from the Antarctic Ice Sheet (AIS). The contribution of surface mass balance changes (due to variable precipitation) is compared with GRACE-derived mass loss acceleration by assessing the estimated contribution of snow mass from meteorological reanalysis data. We find that over much of the continent, the acceleration can be explained by precipitation anomalies. However, on the Antarctic Peninsula and other parts of West Antarctica, mass changes are not explained by precipitation and are likely associated with ice discharge rate increases. The total apparent GRACE acceleration over all of the AIS between 2003 and 2013 is −13.6 ± 7.2 Gt/yr^2. Of this total, we find that the surface mass balance component is −8.2 ± 2.0 Gt/yr^2. However, the GRACE estimate appears to contain errors arising from the atmospheric pressure fields used to remove air mass effects. The estimated acceleration error from this effect is about 9.8 ± 5.8 Gt/yr^2. Correcting for this yields an ice discharge acceleration of −15.1 ± 6.5 Gt/yr^2. ©2015. The Authors. This is an open access article under the terms of the Creative Commons Attribution-NonCommercial-NoDerivs License, which permits use and distribution in any medium, provided the original work is properly cited, the use is non-commercial and no modifications or adaptations are made. Received 9 Nov 2014. Accepted 10 Apr 2015. Accepted article online 14 Apr 2015. Published online 12 May 2015. This work was supported by National Research Foundation grant NRF-2013R1A1A2008368 and Korea Polar Research Institute research grant PM14020. D.W. and B.T.'s contributions were carried out on behalf of the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. GRACE, ERA Interim, MERRA, and NCEP/DOE data are available from GRACE Tellus site (http://grace.jpl.nasa.gov), ECMWF data server (http://data-portal.ecmwf.int), ...
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