Mass changes of polar ice sheets have an important societal impact, because they affect global sea level. Estimating the current mass budget of ice sheets is equivalent to determining the balance between surface mass gain through precipitation and outflow across the grounding line. For the Antarctic ice sheet, grounding line outflow is governed by oceanic processes and outlet glacier dynamics. In this study, we compute the mass budget of major outlet glaciers in the eastern Dronning Maud Land sector of the Antarctic ice sheet using the input/output method. Input is given by recent surface accumulation estimates (SMB) of the whole drainage basin. The outflow at the grounding line is determined from the radar data of a recent airborne survey and satellite-based velocities using a flow model of combined plug flow and simple shear. This approach is an improvement on previous studies, as the ice thickness is measured, rather than being estimated from hydrostatic equilibrium. In line with the general thickening of the ice sheet over this sector, we estimate the regional mass balance in this area at 3.15 ± 8.23 Gt/a according to the most recent SMB model results.

Geographic coordinates were collected with GPS. Surface elevation is the elevation of the plane (from GPS) corrected for the distance between the plane and the surface measured with laser altimeter. Ice thickness is reconstructed by picking the bed wave on radargram collected with 150-Mhz AWI's airborne radar. The two-way travel time is converted into thickness assuming a constant propagation speed of 168E+006 m/s.These data were collected with the financial support of EUropean Facility for Airborne Research (EUFAR, http://www.eufar.net).

Supplement to: Callens, Denis; Thonnard, Nicolas; Lenaerts, Jan T M; van Wessem, Jan Melchior; van de Berg, Willem Jan; Matsuoka, Kenichi; Pattyn, Frank (2015): Mass balance of the Sør Rondane glacial system, East Antarctica. Annals of Glaciology, 56(70), 63-69