Articles | Volume 6, issue 5
The Cryosphere, 6, 1175–1186, 2012

Special issue: Ice2sea – estimating the future contribution of continental...

The Cryosphere, 6, 1175–1186, 2012

Research article 23 Oct 2012

Research article | 23 Oct 2012

Sensitivity of Greenland Ice Sheet surface mass balance to surface albedo parameterization: a study with a regional climate model

J. H. van Angelen1, J. T. M. Lenaerts1, S. Lhermitte2, X. Fettweis3, P. Kuipers Munneke1, M. R. van den Broeke1, E. van Meijgaard2, and C. J. P. P. Smeets1 J. H. van Angelen et al.
  • 1Institute for Marine and Atmospheric Research Utrecht, Utrecht University, The Netherlands
  • 2Royal Netherlands Meteorological Institute, De Bilt, The Netherlands
  • 3Department of Geography, University of Liège, Belgium

Abstract. We present a sensitivity study of the surface mass balance (SMB) of the Greenland Ice Sheet, as modeled using a regional atmospheric climate model, to various parameter settings in the albedo scheme. The snow albedo scheme uses grain size as a prognostic variable and further depends on cloud cover, solar zenith angle and black carbon concentration. For the control experiment the overestimation of absorbed shortwave radiation (+6%) at the K-transect (west Greenland) for the period 2004–2009 is considerably reduced compared to the previous density-dependent albedo scheme (+22%). To simulate realistic snow albedo values, a small concentration of black carbon is needed, which has strongest impact on melt in the accumulation area. A background ice albedo field derived from MODIS imagery improves the agreement between the modeled and observed SMB gradient along the K-transect. The effect of enhanced meltwater retention and refreezing is a decrease of the albedo due to an increase in snow grain size. As a secondary effect of refreezing the snowpack is heated, enhancing melt and further lowering the albedo. Especially in a warmer climate this process is important, since it reduces the refreezing potential of the firn layer that covers the Greenland Ice Sheet.