Meltwater production in Antarctic blue-ice areas: sensitivity to changes in atmospheric forcing

In the near coastal regions of Dronning Maud Land, Antarctica, below-surfac e ice-melt in blue-ice areas has been observed. The low scattering coeffici ents of the large-grained blue-ice allow penetration of solar radiation, th us providing an energy source below the ice surface. The sub-surface meltwa ter is significant enough to show up on remote-sensing imagery in the form of ice-covered lakes. Adjacent snow-accumulation areas have much higher sca ttering coefficients and consequently limit solar radiation penetration in these regions. These snow and ice surfaces are generally below freezing, an d Little surface melting occurs. To assess the response of these melt featu res to changes in atmospheric forcings such as cloudiness, air temperature, and snow accumulation, a physically-based model of the coupled atmosphere, radiation, snow, and blue-ice system has been developed. The model consist s of a heat transfer equation with a spectrally-dependent solar-radiation s ource term. The penetration of radiation into the snow and blue-ice depends on the surface albedo, and the snow and blue-ice grain size and density. M odel simulations show that ice melt occurring in this area is sensitive to potential variations in atmospheric forcing. Under certain conditions more traditional surface melting occurs and, under other conditions, the existin g melt processes can be shut down completely. In light of the sensitivity o f this system to variations in atmospheric forcing, and the ability to view melt-related features using remote sensing, a tool exists to efficiently m onitor variations in Antarctic coastal climate.