Future Changes in Precipitation Extremes in East Asia and Their Uncertainty Based on Large Ensemble Simulations with a High-Resolution AGCM

Future changes in precipitation extremes in East Asia are investigated using large ensemble simulations of about 100 members by a 60-km mesh atmospheric general circulation model (AGCM) for the present climate and 4 K warmer climates, employing six different sea surface temperature (SST) anomaly patterns projected by state-of-the-art climate models. The high-resolution AGCM demonstrates good performance for reproducing precipitation extremes such as annual maximum 1-day precipitation total (Rx1d). Under the warmer climates, Rx1d are robustly projected to increase throughout East Asia. However, there is large range of their quantitative estimates, arising from internal variability and uncertainty in future SST patterns. Over land regions such as inland China, internal variability is the major source of the uncertainty in climatological-mean Rx1d change. However, over oceanic regions including Japan, Korea and coastal China, uncertainty in the SST patterns contributes greatly to the uncertainty in Rx1d through modulation of tropical cyclone activity, suggesting large regional variations in the relative importance of the two sources of uncertainty.