The Cryosphere www.the-cryosphere.net 1994-0416 1994-0424 5 2 2011 10.5194/tc-5-359-2011 http://www.the-cryosphere.net/5/359/2011/ http://www.the-cryosphere.net/5/359/2011/tc-5-359-2011.html http://www.the-cryosphere.net/5/359/2011/tc-5-359-2011.pdf 359 375 2011-05-05 Melting trends over the Greenland ice sheet (1958–2009) from spaceborne microwave data and regional climate models X. Fettweis xavier.fettweis@ulg.ac.be M. Tedesco M. van den Broeke J. Ettema Département de Géographie, Université de Liège, Liège, Belgium City College of New York, City University of New York, New York, NY, 10031, USA Institute for Marine and Atmospheric Research, Utrecht University, Utrecht, The Netherlands To study near-surface melt changes over the Greenland ice sheet (GrIS) since 1979, melt extent estimates from two regional climate models were compared with those obtained from spaceborne microwave brightness temperatures using two different remote sensing algorithms. The results from the two models were consistent with those obtained with the remote sensing algorithms at both daily and yearly time scales, encouraging the use of the models for analyzing melting trends before the satellite era (1958–1979), when forcing data is available. Differences between satellite-derived and model-simulated results still occur and are used here to identify (i) biases in the snow models (notably in the albedo parametrization, in the thickness of a snow layer, in the maximum liquid water content within the snowpack and in the snowfall impacting the bare ice appearance in summer) and (ii) limitations in the use of passive microwave data for snowmelt detection at the edge of the ice sheet due to mixed pixel effect (e.g., tundra or rock nearby the ice sheet). The results from models and spaceborne microwave sensors confirm a significant (p-value = 0.01) increase in GrIS surface melting since 1979. 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