Studies of melting blue ice areas

In the near-coastal regions of Dronning Maud Land, Antarctica,
below-surface ice-melt in blue-ice areas has been observed. The low
scattering coefficients of the large-grained blue-ice, allow
penetration of solar radiation, thus providing an energy source below
the ice surface. The sub-surface meltwater is significant enough to
show up on remote-sensing imagery in the form of ice-covered
lakes. Adjacent snow-accumulation areas have much higher scattering
coefficients and consequently limit solar radiation penetration in
these regions. These snow and ice surfaces are generally below
freezing, and little surface melting occurs. To assess the response of
these melt features 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 is comprised of a heat transfer equation
with a spectrally-dependent solar-radiation source 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. Model 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 existing melt processes can be shut down
completely. In light of the sensitivity of this system to variations
in atmospheric forcing and the ability to view melt-related features
using remote-sensing, a tool exists to efficiently monitor variations
in Antarctic coastal climate. We are currently analysing to what
degree this process contribute to the mass balance of Antarctica The
data set includes: 1) Meteorological data from Jutulgryta, Dronning
Maud Land, 2) Satellite images from Jutulgryta, 3) NOAA AVHRR mosaic
mapping blue ice areas all over the Antarctic continent, 4) albedo
measurements from Jutulgryta, 5) GPS data on surface topography, 6)
Snow temperature records, 7) model results