The Cryosphere Discuss., 6, 4829-4860, 2012
www.the-cryosphere-discuss.net/6/4829/2012/
doi:10.5194/tcd-6-4829-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
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This discussion paper has been under review for the journal The Cryosphere (TC). Please refer to the corresponding final paper in TC.
A new bed elevation dataset for Greenland
J. A. Griggs1, J. L. Bamber1, R. T. W. L. , Hurkmans1, J. A. Dowdesewell2, S. P. Gogineni3, I. Howat4,5, J. Mouginot6, J. Paden3, S. Palmer2, E. Rignot6,7, and D. Steinhage8
1Bristol Glaciology Centre, School of Geographical Sciences, University of Bristol, Bristol, UK
2University of Cambridge, Scott Polar Research Institute, Cambridge UK
3University of Kansas, Center for Remote Sensing Ice Sheets, Lawrence, Kansas, USA
4Ohio State University, School of Earth Sciences, Columbus, Ohio, USA
5Ohio State University, Byrd Polar Research Center, Columbus, Ohio USA
6University of California Irvine, Department of Earth System Sciences, Irvine, California, USA
7Jet Propulsion Laboratory, Pasadena, California, USA
8Alfred Wegener Institute for Polar and Marine Research, Columbusstrasse, Bremerhaven, Germany

Abstract. We present a new bed elevation dataset for Greenland derived from a combination of multiple airborne ice thickness surveys undertaken between the 1970s and 2011. Around 344 000 line kilometres of airborne data were used, with the majority of this having been collected since the year 2000, when the last comprehensive compilation was undertaken. The airborne data were combined with satellite-derived elevations for non glaciated terrain to produce a consistent bed digital elevation model (DEM) over the entire island including across the glaciated/ice free boundary. The DEM was extended to the continental margin with the aid of bathymetric data, primarily from a compilation for the Arctic. Ice shelf thickness was determined where a floating tongue exists, in particular in the north. The across-track spacing between flight lines warranted interpolation at 1 km postings near the ice sheet margin and 2.5 km in the interior. Grids of ice surface elevation, error estimates for the DEM, ice thickness and data sampling density were also produced alongside a mask of land/ocean/grounded ice/floating ice. Errors in bed elevation range from a minimum of ±6 m to about ±200 m, as a function of distance from an observation and local topographic variability. A comparison with the compilation published in 2001 highlights the improvement in resolution afforded by the new data sets, particularly along the ice sheet margin, where ice velocity is highest and changes most marked. We use the new bed and surface DEMs to calculate the hydraulic potential for subglacial flow and present the large scale pattern of water routing. We estimate that the volume of ice included in our land/ice mask would raise eustatic sea level by 7.36 m, excluding any solid earth effects that would take place during ice sheet decay.

Citation: Griggs, J. A., Bamber, J. L., , Hurkmans, R. T. W. L., Dowdesewell, J. A., Gogineni, S. P., Howat, I., Mouginot, J., Paden, J., Palmer, S., Rignot, E., and Steinhage, D.: A new bed elevation dataset for Greenland, The Cryosphere Discuss., 6, 4829-4860, doi:10.5194/tcd-6-4829-2012, 2012.
 
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