LONGWAVE RADIATION ON SNOW-COVERED MOUNTAINOUS SURFACES

Longwave radiation in snow-covered alpine environments was investigate d based on LOWTRAN7 calculations, The irradiance from the sky and from the surrounding topography were determined separately in order to det ect the influence of the topography on longwave radiation balance. Sen sitivity studies showed that the irradiance from the surrounding terra in is determined primarily by the atmospheric conditions within the in vestigated area and by the surface temperature of the surrounding terr ain. In snow-covered environments, the air temperature is usually abov e the snow surface temperature and the effects of the air between the topography and the receiving surface may be relevant. Longwave irradia nce from the surrounding terrain is an important component of the ener gy balance at the snow surface on inclined slopes and should be consid ered for areal investigations. A simple parameterization that accounts for the effects of the air is proposed for efficient calculation of l ongwave irradiance from snow-covered topography.