Projecting Changes in Mean and Extreme Precipitation Over Eastern China During 2041-2060

This report summarizes the preliminary analysis of the PRECIS 2.0 simulation results, with an emphasis on the priority concerns of Shanghai municipal government and other local governments in the Yangtze River Delta (YRD) Region, and research gaps in the literature. This study employs two regional climate models (RCMs) that are the Providing REgional Climate Impacts for Studies (PRECIS) and Weather Research and Forecasting (WRF), being driven by HadGEM2-ES and IPSL-CM5A, two global circulation models (GCMs) from the Coupled Model Intercomparison Project Phase 5 (CMIP5), to investigate the impact of global warming on the characteristics of mean and extreme precipitation over Eastern China. The capacity of two RCMs and its driving GCMs in reproducing the historical climate during the baseline period (1981-2000) are first evaluated, and then the projections of mean and extreme precipitation over future warming climate period (2041-2060) under the scenarios of the Representative Concentration Pathways (RCPs) 4.5 and 8.5 are carried out. Our analysis shows that with the improved resolution and better representation of finer-scale physical processes, WRF and PRECIS downscaling displays obvious advantages over their driving GCMs (IPSL and HadGEM, respectively) in the validation runs. In particular, the two RCMs are able to capture the observed features of spatial distributions of extreme precipitation indices including V95p, R95t, and SDII. The future projections indicate that increased radiative forcing from RCP4.5 to RCP8.5 emission scenarios would add further strength to the daily precipitation intensity by 2041-2060.