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

• Published in: The cryosphere Vol. 6; no. 5; pp. 1175 - 1186
• Main Authors: van Angelen, J. H, Lenaerts, J. T. M, Lhermitte, S, Fettweis, X, Kuipers Munneke, P, van den Broeke, M. R, van Meijgaard, E, Smeets, C. J. P. P
• Format: Journal Article Web Resource
• Language: English
• Published: Katlenburg-Lindau Copernicus GmbH 23.10.2012; Copernicus; Copernicus Publications
• Subjects: Analysis; Climate models; Earth sciences & physical geography; Ice sheets; Physical, chemical, mathematical & earth Sciences; Physique, chimie, mathématiques & sciences de la terre; Sciences de la terre & géographie physique; PN, Greenland, Greenland Ice Sheet; Greenland
• ISSN: 1994-0424; 1994-0416; 1994-0424; 1994-0416
• DOI: 10.5194/tc-6-1175-2012

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.