Validation of the Snow Cover Variation of the Canadian Regional Climate Model (CRCM) Using Passive Microwave Satellite Data

The spatial/temporal variation of the snow cover can be simulated by models such as the Canadian Regional Climate Model (CRCM) developed by Universite du Quebec a Montreal that simulates the snow water equivalent (SWE), a key parameter for hydrological cycle investigation. Better understanding of snow cover dynamics and the validation of these models suffer from the sparse observational record available and passive microwave satellite data appears as a very useful tool for such an objective. The data are derived from the daily Special Sensor Microwave / Imager (SSM/I) data from the DMSP satellite time series and also from the Northern Hemisphere Weekly Snow Cover and Ice Extent from the NSIDC in the EASE-Grid format. A threshold adapted for four vegetation density classes (derived from the AVHRR Canadian land cover 1km-resolution image) is applied to the normalized difference brightness temperature signal between 37GHz and 19GHz to extract snow cover. This satellite database was compared to a short CRCM run simulation driven by the NCEP atmospheric objective analysed for the period between August 1992 and June 1995 over Eastern Canada. The results show that the model underestimates snow cover, the snow onset tending to arrive later and the snow melting faster in spring compared to SSM/I. For the overall studied area, it appears that the CRCM is modeling snow cover with an error of 9.3% in term of number of days. Locally, this error can be as large as 30–40%. This paper shows the potential of satellite microwave data for the comprehensive spatial and temporal evaluation of model behavior.