Climate Extremes in a High-Resolution Regional Model Ensemble over the Continental United States

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Monday, 5 January 2015
Deeksha Rastogi, ORNL, Oak Ridge, TN; and R. Mei and M. Ashfaq

There is no doubt that more weather extremes are coming our way if increase in radiative forcing remains unchecked during the 21st century. Better regional and local-scale climate projections are imperative for communities to prepare for the adverse effects of climate change. Here, we generate and analyze a high-resolution ensemble of climate projections over the continental U.S. to investigate the mechanisms that drive fine-scale precipitation and temperature extremes in the near term 20th century and that how future changes in those mechanisms will affect the likelihood of such events over the next several decades. Our high-resolution ensemble consist of 12 members of a regional climate model (RCM) simulations at 18km horizontal grid spacing, with each member representing 41 years (1965-2005) in the historical period and 41 years in the future (2010-2050) period under the Representative Concentrations Pathway 8.5. The initial and boundary conditions for these 12 RCM ensemble members are derived from 12 Global Climate Models (ACCESS1-0, bcc-csm1-1, CanESM2, CCSM4, CMCC-CM, FGOALS-g2, GFDL-ESM2M, IPSL-CM5A-LR, MIROC5 MPI-ESM-MR, MRI-CGCM3, NorESM1-M) in the 5th phase of Coupled Model Intercomparison Project. The study shows a generally decreasing trend in number of wet days over most part of the US whereas an overall increase in extreme precipitation days. Similarly, extreme temperature events also tend to show an increase in future time period. These results highlight the need for more regional and local adaptation and mitigation strategies in the coming decades.