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The Canadian Prairies have experienced severe and extended droughts that have had significant impacts on agriculture, energy and other socio-economic sectors; it is therefore desirable to assess future changes to drought characteristics in this drought prone region, in the context of a changing climate. This study addresses validation and projected changes to short- and long-term drought characteristics, i.e. severity, frequency and duration, over the Canadian Prairies, using an ensemble of ten Canadian RCM (CRCM) simulations, of which five correspond to the current 1971-2000 period and the other five are the matching simulations for the future 2041-2070 period. These five pairs of current and future CRCM simulations were driven by five different members of a Canadian Global Climate Model ensemble. Validation of CRCM simulated precipitation suggests that the model reproduces the observed precipitation distribution for all seasons, except summer, across a large portion of the Canadian Prairies. However, comparison of CRCM simulated drought characteristics with those observed suggests that the model has difficulties in reproducing observed severity, frequency and duration of drought events, particularly those associated with longer events, possibly due to the overestimation of summer precipitation by the model. Analysis of projected changes to precipitation and drought characteristics between the 1971-2000 and 2041-2070 periods suggests a decrease in mean precipitation in summer and an increase for the other seasons, while the severity, frequency and maximum duration of both short- and long-term droughts are projected to increase over the southern Prairies, with the largest projected changes associated with longer drought events. Classification of the watersheds spanning the southern Prairies based on changes to both severity and frequency further reveal the vulnerability of this region in a changing climate. Copyright © 2012 Royal Meteorological Society [ABSTRACT FROM AUTHOR]

The present study focuses on the evaluation and comparison of the ability of two versions of the Canadian Regional Climate Model (CRCM) driven by re-analyses (NCEP-NCAR) to reproduce the observed extremes and climate variability in summer (1961-1990). The analysed variables are daily precipitation, minimum and maximum temperatures over three regions located in north-eastern North America that are characterized by different topography and observation density. The validation has been performed with multiple climate extreme indices characterizing the frequency, intensity and duration of precipitation and temperature events. The assessment of the ability of the CRCM is done through an in-depth analysis of the statistical distribution, performance scores and interannual variability of extreme indices. The reference database has been constructed by kriging the daily observed data from local meteorological stations onto the CRCM 45-km grid. The vast majority of results over the three regions show that, with respect to the previous (i.e. 3.7.1) CRCM version, the latest version (4.1.1) improves in general the simulated extreme events. In particular, the intensity of extreme hot summer temperature, diurnal temperature range, wet days occurrence, seasonal dry spell, and to a lesser extent extreme cold summer temperature and heavy rainfall. The study suggests that improvements in the simulated extremes in the latest version are due mainly to the introduction of the new land surface scheme (CLASS 2.7), with a more sophisticated representation of the soil moisture content. This suggests the importance of surface processes parameterization as a potential cause of errors in simulated extremes. Copyright © 2011 Royal Meteorological Society [ABSTRACT FROM AUTHOR]