Although the snow albedo feedback mechanism has been shown to amplify global
warming effects in nearly all models of global climate, it continues to be
represented as a simplistic parameterization. Here, we demonstrate how
changes in snow-pack energy-balance drive the seasonal fluctuations in snow
albedo for the Greenland ice sheet. For a detailed, point-based
investigation of the relationship between snowpack energy balance and
albedo, two models are coupled together; one that calculates snow grain-size
and the other that uses those grain-size data as input to a
radiative-transfer code to obtain spectral albedo. These data indicate that
in the near-infrared wavelengths, albedo values drop nearly 20%, during a 10
day period during which grain-sizes increased dramatically. Satellite data
were used to map monthly changes in albedo over the entire Greenland ice
sheet during the spring and summer months. These monthly albedo images
indicate albedo reductions of as much as 80% in coastal regions. Even in
areas that experience little or no melt, albedo decreases of 10–20% were
common. From these results, it is clear that snow albedo parameterizations
for climate models must incorporate the dynamics of snowpack energy
balance.