Analysis of climatic factors leading to future summer heatstroke risk changes in Tokyo and Sendai based on dynamical downscaling of pseudo global warming data using WRF

This study aims to clarify the regional characteristics of climate change and its impact on heatstroke risk inside the cities of Tokyo and Sendai, Japan. First, meteorological simulations using the Weather Research and Forecasting model (WRF) were performed. Pseudo global warming data were used as the boundary conditions for WRF simulations for the global-scale current and future climates in the 2000s and 2050s. The increase in wet-bulb globe temperature (WBGT) was larger in Sendai than in Tokyo, and the increase in WBGT in the coastal areas of both cities became larger than that in the inland area. Then, heatstroke risk and incidence rate, which represent the potential risk, were analyzed based on the WBGT distribution. Furthermore, contributions of three types of temperature (wet-bulb, globe, and dry-bulb temperatures) in increasing the WBGT were analyzed in order to clarify the primary meteorological factors for the increase in WBGT in each region. It was found that the wet-bulb temperature is the dominant factor in the increase in WBGT in most regions.