1Earth and Space Sciences, University of Washington, Seattle, WA, USA
2Polar Science Center, Applied Physics Lab, University of Washington, Seattle, WA, USA
3Geology and Geophysics, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
4Quaternary Research Center, University of Washington, Seattle, WA, USA
5Center for Remote Sensing of Ice Sheets, University of Kansas, Lawrence, KS, USA
6MIT/WHOI Joint Program in Oceanography/Applied Ocean Sciences and Engineering, Woods Hole Oceanographic Institution, Woods Hole, MA, USA
7Desert Research Institute, Nevada System of Higher Education, Reno, NV, USA
8Institute for Marine and Atmospheric Research Utrecht, Utrecht University, Utrecht, the Netherlands
9Polar Meteorology Group, Byrd Polar Research Center, and Atmospheric Sciences Program, Department of Geography, The Ohio State University, Columbus, OH, USA
Received: 17 Dec 2013 – Discussion started: 06 Feb 2014
Abstract. In Antarctica, uncertainties in mass input and output translate directly into uncertainty in glacier mass balance and thus in sea level impact. While remotely sensed observations of ice velocity and thickness over the major outlet glaciers have improved our understanding of ice loss to the ocean, snow accumulation over the vast Antarctic interior remains largely unmeasured. Here, we show that an airborne radar system, combined with ice-core glaciochemical analysis, provide the means necessary to measure the accumulation rate at the catchment-scale along the Amundsen Sea coast of West Antarctica. We used along-track radar-derived accumulation to generate a 1985–2009 average accumulation grid that resolves moderate- to large-scale features (>25 km) over the Pine Island–Thwaites glacier drainage system. Comparisons with estimates from atmospheric models and gridded climatologies generally show our results as having less accumulation in the lower-elevation coastal zone but greater accumulation in the interior. Ice discharge, measured over discrete time intervals between 1994 and 2012, combined with our catchment-wide accumulation rates provide an 18-year mass balance history for the sector. While Thwaites Glacier lost the most ice in the mid-1990s, Pine Island Glacier's losses increased substantially by 2006, overtaking Thwaites as the largest regional contributor to sea-level rise. The trend of increasing discharge for both glaciers, however, appears to have leveled off since 2008.
Revised: 07 May 2014 – Accepted: 05 Jun 2014 – Published: 31 Jul 2014
Medley, B., Joughin, I., Smith, B. E., Das, S. B., Steig, E. J., Conway, H., Gogineni, S., Lewis, C., Criscitiello, A. S., McConnell, J. R., van den Broeke, M. R., Lenaerts, J. T. M., Bromwich, D. H., Nicolas, J. P., and Leuschen, C.: Constraining the recent mass balance of Pine Island and Thwaites glaciers, West Antarctica, with airborne observations of snow accumulation, The Cryosphere, 8, 1375-1392, doi:10.5194/tc-8-1375-2014, 2014.