Assessment of the RegCM4 over East Asia and future precipitation change adapted to the RCP scenarios

In this study, we investigated spatial and temporal changes in precipitation over the Coordinated Regional Climate Downscaling Experiment (CORDEX) East Asia domain, for present (1986-2005) and future (2031-2050) periods using the Regional Climate Model version 4 (RegCM4). Future meteorology produced by the Hadley Center Global Environmental Model version 2 coupled with the Atmosphere-Ocean (HadGEM2-AO) following global climate change scenarios (Representative Concentration Pathways (RCP) 4.5 and 8.5) was used as meteorological boundary conditions for the RegCM4. Six subregions (South Korea, North China, South China, Japan, Mongolia, and India) in the CORDEX East Asia domain were considered for analysis. The RegCM4 simulated spatial distributions of precipitation over East Asia with a correlation coefficient of 0.7 against Climate Research Unit data. The simulation skills of its temporal variability varied based on geographical regions and seasons, showing relatively poorer performance (underestimation in rainfall amount) in summer than in winter, in general. The future climate simulations by the RegCM4 presented that the East Asian continental regions will be warmer and more humid, leading to increased precipitation amounts, especially in the summer. The summer precipitation amount was projected to increase by about 5%, on average, over the East Asian domain, 5-15% in most subregions, and even higher (44% and 24%) in the South Korean region for the RCP 4.5 and 8.5 scenarios, respectively. It was also expected that heavy rainfall (> 50 mm/d) events may occur more frequently in the future possibly owing to meteorological changes that are favorable to convective heavy precipitation.