THE SURFACE-ENERGY BALANCE OF ANTARCTIC SNOW AND BLUE ICE

Little is known about the surface energy balance of Antarctic blue-ice areas although there have been some studies of the surface energy bal ance of snow surfaces. Therefore, a detailed meteorological experiment was carried out in the vicinity of a blue-ice area in the Heimefrontf jella, Dronning Maud Land, Antarctica, during the austral summer of 19 92/93. Since not all the surface fluxes could be measured directly, th e use of a model was necessary. The main purpose of the model is to ca lculate the surface and subsurface temperatures from which the emitted longwave radiation and the turbulent fluxes can be calculated. The su rface energy balance was evaluated at four locations: one on blue ice, and three on snow. Differences are due mainly to the fact that ice ha s a lower albedo (0.56) than snow (0.80). To compensate for the larger solar absorption of ice, upward fluxes of longwave radiation and turb ulent fluxes are larger over ice. Moreover, the energy flux into the i ce is larger than into snow due to the differences in the radiative an d conductive properties. Surface temperatures, snow subsurface tempera tures, and ice sublimation rates evaluated with the model compare well with the measurements, which yields confidence in the surface energy balance results. The latent heat flux is particularly important since the spatial variability of the sublimation rates largely influences th e extent of a blue-ice area. This study helps to explain the heat exch ange processes over Antarctic surfaces.