Investigation of regional climate models’ internal variability with a ten-member ensemble of 10-year simulations over a large domain
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Previous investigations on regional climate models’ (RCM) internal variability (IV) were limited owing to small ensembles, short simulations and small domains. The present work extends previous studies with a ten-member ensemble of 10-year simulations performed with the Canadian Regional Climate Model over a large domain covering North America. The results show that the IV has no long-term tendency but rather fluctuates in time following the synoptic situation within the domain. The IV of mean-sea-level pressure (MSLP) and screen temperature (ST) show a small annual cycle with larger values in spring, which differs from previous studies. For precipitation (PCP), the IV shows a clear annual cycle with larger values in summer, as previously reported. The 10-year climatology of the IV for MSLP and ST shows a well-defined spatial distribution with larger values in the northeast of the domain, near the outflow boundary. A comparison of the IV of MSLP and ST in summer with the transient-eddy variance reveals that the IV is close to its maximum in a small region near the outflow boundary. Same analysis for PCP in summer shows that the IV reaches its maximum in most parts of the domain, except for a small region on the western side near the inflow boundary. Finally, a comparison of the 10-year climate of each simulation of the ensemble showed that the IV may have a significant impact on the climatology of some variables.
KeywordsInternal variability Regional climate models Ensemble of simulations North American climate Ten-year simulations
This work is part of the Ph.D. thesis of Philippe Lucas-Picher in Environmental Sciences at Université du Québec at Montréal. The authors wish to thank Claude Desrochers and Mourad Labassi for maintaining a user-friendly local computing environment at the Ouranos Consortium. A special thank is directed to Sébastien Biner and Samuel Somot, which generously devoted time to the discussion of some sections of the manuscript. This work was carried out as part of the research programs of the Canadian Climate Variability Research Network (CLIVAR), the Canadian Network for Regional Climate Modelling and Diagnostics (CRCMD) and the Ouranos Consortium. It was financially supported by the Canadian Foundation for Climate and Atmospheric Sciences (CFCAS), the National Science and Engineering Research Council of Canada (NSERC) and the Ouranos Consortium. Finally, the authors would like to thank Dr. Maryse Picher for her careful revision that has improved the readability of the manuscript.
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