Is snow sublimation important in the alpine water balance?

U. Strasser (1) , M. Bernhardt (1) , M. Weber (2) , G. E. Liston (3) , W. Mauser (1)

1 Department of Geography
2 Commission for Glaciology
3 CIRA - Cooperative Institute for Research in the Atmosphere

In alpine terrain, snow sublimation as a component of the winter moisture budget represents a proportion of precipitation which does not contribute to melt. To quantify its amount we analyze the spatial pattern of snow sublimation at the ground, from a canopy and from turbulent suspension during wind-induced snow transport for a high alpine area in the Berchtesgaden National Park (Germany), and we discuss the efficiency of these processes with respect to seasonal snowfall. Therefore, we utilized hourly meteorological recordings from a network of automatic stations, and a distributed simulation framework comprising validated, physically based models. Meteorological data records were spatially distributed over the simulation domain by means of a quasi-physically based interpolation scheme that accounts for topographic influences on the distributed fields. The applied simulation tools were: a detailed model for shortwave and longwave radiative fluxes, a mass and energy balance model for the ground snow cover, a model for the microclimatic conditions within a forest canopy and related snow-vegetation interactions including snow sublimation from the surface of the trees, and a model for the simulation of wind-induced snow transport and related sublimation from suspended snow particles. For each of the sublimation processes, mass rates were quantified and aggregated over an entire winter season. Sublimation from the ground and from most canopy types are spatially relatively homogeneous and sum up to about 100 mm of snow water equivalent (SWE) over the winter period. Accumulated seasonal sublimation due to turbulent suspension is small in the valley areas, but can locally, at very wind-exposed mountain ridges, add up to more than 1000 mm of SWE. The fraction of these sublimation losses of winter snowfall is between 10 and 90%.

Domaines: Interfaces continentales, environnement; Océan, Atmosphère; Sciences de la Terre

U. Strasser, M. Bernhardt, M. Weber, G. E. Liston, W. Mauser. Is snow sublimation important in the alpine water balance?. The Cryosphere Discussions, 2007, 1 (2), pp.303-350. ⟨hal-00298531⟩