11.5
Potential Influence of Climate Change on Atmospheric Rivers Induced Heavy Precipitation and Flooding in the Western US
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As part of the North American Regional Climate Change Assessment Program (NARCCAP), simulations have been performed using the Weather Research and Forecasting (WRF) model for North America at 50 km horizontal resolution. Three sets of simulations, one driven by large-scale conditions from the NCEP/DOE global reanalysis for 1980-1999, and two driven by the Community Climate System Model (CCSM) for 1970 - 2000 and 2040 - 2070 have been performed for North America at 50 km grid resolution. Analysis of the large-scale environments simulated by CCSM for the current and future climate suggests a 27% increase in frequency of atmospheric rivers that make landfall in the US west coast. In addition, the atmospheric rivers carry 7 – 12% more atmospheric moisture in the future climate. Analysis, focusing on both the atmospheric and land surface influence on floods, is being performed using the downscaled simulations to assess the impacts of climate change on heavy precipitation and flooding in the western US.