The Cryosphere Discussions www.the-cryosphere-discuss.net 1994-0432 1994-0440 4 1 2010 10.5194/tcd-4-233-2010 http://www.the-cryosphere-discuss.net/4/233/2010/ http://www.the-cryosphere-discuss.net/4/233/2010/tcd-4-233-2010.html http://www.the-cryosphere-discuss.net/4/233/2010/tcd-4-233-2010.pdf 233 285 2010-03-12 The effect of more realistic forcings and boundary conditions on the modelled geometry and sensitivity of the Greenland ice-sheet E. J. Stone emma.j.stone@bristol.ac.uk D. J. Lunt I. C. Rutt E. Hanna BRIDGE, School of Geographical Sciences, University of Bristol, UK School of the Environment and Society, Swansea University, UK Department of Geography, University of Sheffield, Sheffield, UK Ice thickness and bedrock topography are essential boundary conditions for numerical modelling of the evolution of the Greenland ice-sheet (GrIS). The datasets currently in use by the majority of Greenland ice-sheet modelling studies are over two decades old and based on data collected from the 1970s and 80s. We use a newer, high-resolution Digital Elevation Model of the GrIS and new temperature and precipitation forcings to drive the Glimmer ice-sheet model offline under steady state, present day climatic conditions. Comparisons are made in terms of ice-sheet geometry between these new datasets and older ones used in the EISMINT-3 exercise. We find that changing to the newer bedrock and ice thickness makes the greatest difference to Greenland ice volume and ice surface extent. When all boundary conditions and forcings are simultaneously changed to the newer datasets the ice-sheet is 25% larger in volume compared with observation and 11% larger than that modelled by EISMINT-3. <br><br> We performed a tuning exercise to improve the modelled present day ice-sheet. 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