Regional projection of tropical-cyclone-induced extreme precipitation around Japan based on large ensemble simulations

Abstract

This study investigated future changes in extreme precipitation associated with tropical cyclones (TCs) around Japan using large ensemble regional climate simulations for historical and +4 K climates. Under the warmer climate, extreme TC precipitation, defined as the 90th percentile value of the maximum daily precipitation derived from each TC (TCP90), is projected to increase throughout Japan from Kyushu to Kanto. We attributed most of the increase in TCP90 to increased atmospheric moisture due to global warming. Furthermore, it was found that TCP90 is projected to increase for all TC intensity categories. However, the projected increase in intense TCs affects TCP90 in only a limited area. Stronger TCs enhance TCP90 over east- and north-facing slopes of mountainous terrain, while TCP90 in most other areas is insensitive to TC intensity. These results suggest that even relatively weak TCs could have potential to produce extreme precipitation that might cause natural disasters.