Probabilistic Assessment of Meteorological Drought Risk over the Canadian Prairie Provinces Based on the NARCCAP multi-RCM Ensemble

Abstract:

This study assesses projected changes to drought characteristics in Alberta, Saskatchewan and Manitoba, the prairie provinces of Canada using a multi-Regional Climate Model (RCM) ensemble available through the North American Regional Climate Change Assessment Program. Simulations considered include those performed with six RCMs for the 1981–2003 period driven by National Centre for Environmental Prediction reanalysis II and by four Atmosphere–Ocean General Circulation Models for the 1970–1999 and 2041–2070 periods (11 current-to-future period simulation pairs). Drought characteristics are extracted using two drought indices, namely Standardized Precipitation Index (SPI), which is solely based on precipitation, and the Standardized Precipitation Evapotranspiration Index (SPEI), which is based on both precipitation and temperature in the form of evapotranspiration. Regional frequency analysis is used to project changes to selected 20- and 50-yr regional return levels of drought for fifteen homogeneous regions. In addition, multivariate analyses of drought characteristics, derived on the basis of SPI and SPEI values of six month time scale, are developed using the copula approach for each region. Results reveal that analysis of multi-RCM ensemble-averaged projected changes to drought characteristics and various return levels of drought characteristics show increases over the southern, western and eastern parts of the study area. Based on bi- and trivariate joint occurrence probabilities of drought characteristics, the southern regions along with the central regions are found highly drought vulnerable, followed by southwestern and southeastern regions. These projections will be useful in the development of appropriate adaptation strategies for the water and agricultural sectors, which play an important role in the economy of the study area.