89th American Meteorological Society Annual Meeting

Sunday, 11 January 2009
Impacts of climate change on the summer rainfall of the Southern Rocky Mountains
Phoenix Convention Center
Roque Vinicio Céspedes, Univ. of Miami/RSMAS, Hialeah, FL; and G. J. Holland and R. D. Loft
In an attempt to better understand how summer rainfall in the Southern Rocky Mountains region may be changing due to Global Warming, simulations from the National Center for Atmospheric Research (NCAR) Nested Regional Climate Model (NRCM) for summer 1970 and summer 2020 were compared and contrasted. The NRCM is unique in that it combines the global climate simulation capabilities of the Community Climate System Model (CCSM) with the regional forecasting capabilities of the Weather Research and Forecasting (WRF) model in an attempt provide more accurate high-resolution regional climate simulations. The IPCC (Intergovernmental Panel on Climate Change) scenario A2 (“business as usual” emissions) was used for these NRCM runs. For this study, the NRCM was run at a horizontal resolution of 36 km. The model predicts increased summer rainfall totals in summer 2020 when compared to summer 1970. Average NRCM summer temperature was found to be lower in 2020, probably as a result of increased rainfall and more mid-afternoon convective clouds. Surface elevation was found to definitely have an effect on both the simulated rainfall and surface temperature. Overall, higher elevations experienced fewer changes in both summer accumulated rainfall and average surface temperature. Due to the limited data set available from the NRCM at the time of this study, longer time periods need to be compared, as more NRCM simulation data becomes available, in order to determine if what is observed here is a climate change trend, or the result of natural inter-annual variability.

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