On Snowmelt Computations in the Climate Change Context: Comparison of Single Site and Multisite Downscaling of Extreme Daily Temperature Processes

This study focuses on how multisite downscaling procedures can provide a significant improvement in the accuracy of impact assessment results as compared to single-site downscaling techniques. The study compared the accuracy of snowmelt computations given by the multisite multivariate statistical downscaling (MMSD) method and the single site downscaling (SDSM) procedure. Results of an illustrative application using daily maximum (Tmax) and minimum (Tmin) temperature series at seven stations in southern Quebec-Ontario region in Canada indicated that MMSD method was able to reproduce accurately the observed spatial and temporal variabilities of daily extreme temperature processes over different locations. MMSD approach preserved more accurately the interstation correlations of daily Tmax (0.78 and 0.7) and Tmin (0.94 and 0.84) respectively for calibration and validation period than SDSM (0.08 and 0.11 for Tmax; and 0.02 for Tmin). MMSD was found capable to produce more accurate snowmelt estimations than those given by the SDSM.