Validation of 1-D Snow-Cover Simulations
by the CLASS Land Surface Scheme for GCMs
Ross Brown1
The Canadian Land Surface Scheme for GCMs (CLASS; Verseghy 1991) employs a simplified
one-layer treatment of the snowpack. It has been stated (Loth et al. 1993, Lynch-Stieglitz 1994) that
multilayer models are required to resolve the characteristic steep near-surface temperature and
vapor gradients in a snowpack in order to successfully model snowpack processes. This paper
compared CLASS snowpack simulations with those of a detailed multilayer model (CROCUS;
Brun et al. 1992) with meteorological and snow data from measurement sites in different snow
climate zones. The one-layer model was observed to exhibit a consistent cold bias in snow surface
temperature and underestimated the aging of snow during the snow season. In spite of these prob-
lems, the one-layer model was able to provide realistic simulations of interannual and seasonal
variation in important snowpack properties (albedo, snow cover, snow depth, SWE, and runoff).
References:
Brun, E., P. David, M. Sudul, and G. Brunot (1992) A numerical model to simulate snow-cover
stratigraphy for operational avalanche forecasting. J. Glaciol., 38: 1322.
Loth, B., H.F. Graf, and J.F. Oberhuber (1993) Snow cover model for global climate simulations.
J. Geophys. Res., 98(D6): 10,45119,464.
Lynch-Stieglitz, M. (1994) The development and validation of a simple snow model for the GISS
GCM. J. Climate, 7: 18421855.
Verseghy, D. (1991) CLASS--A Canadian land surface scheme for GCMS. I: Soil model. Int. J.
Climatol., 11: 111133.
1
Atmospheric Environment Service, 2121 Trans-Canada Highway, Dorval, QC, H9P IJ3, Canada
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