MEASUREMENT AND SIMULATION OF THE ENERGY AND MASS BALANCE OF SNOW AT AN ALPINE VALLEY SITE

This investigation is based on data collected during a comprehensive field campaign focussing on air pollution and noise aspects in the lower Inntal valley (Austria) during winter 2005/2006. In this context, the evolution of snow plays an important role too, e.g. with respect to the strength and persistence of inversions. This is of particular interest in view of the exceptional situation during winter 2005/2006, which was characterized by an almost unbroken snow cover all over the country. A one-dimensional mass and energy balance model is successfully used to simulate the seasonal evolution of the snow pack and its interaction with the atmosphere and the underlying soil. Profiles of snow temperature and density, grain size, or liquid water content are predicted by numerically solving for the governing equations of the relevant processes. The model is driven by the basic meteorological parameters and validation of the simulation results is based on com-parison with a set of independent measurement data. The energy balance during the accumulation period was characterized by a net loss due to radiation and the prevalence of evaporation, which was offset by the positive contributions from turbulent sensible and conductive soil heat fluxes. During the melt period, the snow pack experienced enhanced energy input, which was mainly associated to the now positive radiation budget and the soil heat flux directed towards the surface. The initial ablation rates were significantly enhanced as soon as melt water and solar radiation approached the snow-soil interface