11:30 AM - 11:45 AM
[AAS07-04] Impact of Historical and Future Warming on Heavy Rainfall Over Eastern Japan Induced by Typhoon Hagibis (2019) in Dynamical Downscaling Simulations
Keywords:global warming, typhoon, heavy precipitation
To investigate the impact of historical and future warming on heavy rainfall induced by Typhoon Hagibis (2019), we conducted several dynamical downscaling simulations using the Weather Research and Forecasting Model with a horizontal resolution of 5 km: a control simulation of Hagibis (referred to as CTL run), pseudo global warming experiments with 2-K and 4-K warmed scenarios (referred to as 2K and 4K runs), and a non-warming experiment (referred to as NW run). Total rainfall in the Kanto (Tohoku) regions changed by −4% (−5%), +4% (+11%), and +11% (+23%) in the NW, 2K, and 4K runs, respectively, with respect to that in the CTL run. The regional differences in total rainfall changes originated from Hagibis' precipitation systems under warming climates. Historical and future warming led to a well-developed convectively unstable layer with a very humid condition in the middle troposphere on the north-to-northwest of Hagibis. Such a favorable environment for heavy rainfall systems contributed to a precipitation increase in the western-to-northern sectors of Hagibis, where the outer-rainband was unclear in the CTL run, leading to the formation of a strong convective outer-rainband of Hagibis under a future warmed climate. The widespread and intense outer-rainband expanded the heavy rainfall area over the Kanto (Tohoku) regions by −5% (−11%), +6% (+22%), and +15% (+52%) in the NW, 2K, and 4K runs, respectively, with respect to that in the CTL run. The result suggests a significant increase in flooding risk due to Hagibis-like typhoons under the future climate, especially in the Tohoku area.