Identifying a new normal in extreme precipitation at a city scale under warmer climate regimes: A case study of the Tokyo metropolitan area, Japan

Here, we investigate the change of hourly EP caused by warmer climate regimes in a large urban agglomeration in midlatitude, Tokyo, Japan. We use pseudo-global warming dynamical downscaling approach with a convection-permitting regional climate model considering two Representative Concentration Pathways scenarios 8.5 and 4.5 to simulate the August climate for the present (2005-2014) and the future time (up to 2100).

The results show a substantial enhancement of local hourly precipitation regarding both frequency and intensity. Framing the change with Clausius-Clapeyron (CC) scaling relation, which is of approximately 7% per K warming, we confirmed the paradigm of "extreme gets more extreme" in the future local hourly precipitation. The 0.99 quantile precipitation is intensified at the super CC scaling rate (3 CC); whereas the intensification of lower-quantile precipitation is at the sub-CC rate.