Simulations of future typhoons and storm surges around Tokyo Bay using IPCC AR5 RCP 8.5 scenario in multi global climate models

The object of the present study is to numerically evaluate the characteristics of future potential typhoons and storm surges around Tokyo Bay under a RCP8.5 scenario usinga simple one-way model system composed of ARW-WRF and FVCO. In order to evaluate the effect of the expected future increase in sea surface temperature (SST), air temperature (AT) and relative humidity (RH) four types of cases were considered in the 2041–2060 and 2081–2100 horizons. The results show how higher SST will likely lead to more intense typhoons and storm surges, though higher AT in troposphere and tropopause will somehow moderate this effect. In addition, a simple method to estimate the most influential wind direction that can generate surge elevations in Yokohama, Tokyo and Funabashi was examined by using the results of a numerical simulation. Finally, a simple methodology to calculate the required design height of sea walls and dykes in Tokyo Bay was developed, which shows how current design levels will be insufficient to maintain the present acceptable risk levels in the area.