Comparison of AVHRR-derived and in situ surface albedo over the Greenland ice sheet

This paper discusses a methodology for computing the clear-sky surface albedo over the Greenland ice sheet by using advanced very high resolution radiometer (AVHRR) global area coverage visible and near-infrared reflectances. This approach is then used to map the monthly changes in albedo over the entire Greenland ice sheet during the spring and summer months. The methodology includes corrections for the intervening atmosphere by using the 6S radiative transfer model. Additional corrections for the anisotropic nature of snow reflectance and the conversion from a narrow- into a broadband albedo are made based on in situ measurements from the Swiss Federal Institute of Technology University of Colorado camp at 69-degrees-34'N, 49-degrees-18'W. Comparison with surface albedo field measurements indicates that before the onset of snow melt, agreement is good between the satellite-derived and measured surface albedo. After melt begins, it is difficult to compare the satellite values with the field data owing to melt water ponding on the ice sheet surface. With appropriate modifications, the 6S radiative transfer model is suitable for atmospherically correcting AVHRR visible and near-infrared radiances in polar regions.