Providing high-resolution heatstroke risk predictions for an artificial island in Osaka Bay

Due to the effects of global warming in recent years, there are concerns that the damage caused by heatstroke will increase in Japan as well. To evaluate the risk of heatstroke, a meteorological model capable of calculating micrometeorology considering the effects of buildings and trees is necessary. The Multi-Scale Simulator for the Geoenvironment (MSSG) developed by the Japan Agency for Marine-Earth Science and Technology (JAMSTEC) is a multi-scale atmosphere-ocean coupled model capable of calculating from the global scale to the regional scale and urban scale. Its atmospheric component allows for micrometeorological calculations with a resolution of several meters considering the three-dimensional shapes of buildings and tree canopies.

The Japan Meteorological Agency distributes forecast data called the Meso Spectral Model (MSM). In this study, downscaling was performed using MSSG with this MSM data as the initial and boundary values, and micrometeorological calculations at the urban scale were performed. In addition, WBGT, an index of heatstroke risk, was calculated from the results of the micrometeorological calculations and predicted values of heatstroke risk were provided via a web server.

On the day the prediction calculation was performed, we measured WBGT on-site using a black globe thermometer to confirm the accuracy of the heatstroke risk prediction. In the area behind the building, where the wind is weak, and in the corridor, where the wind is strong, both the measured and predicted WBGT values were lower in the corridor. However, there was a tendency for the predicted WBGT values to be uniformly lower than the measured values. By measuring temperature and relative humidity, it is possible to calculate the WBGT when the measured values are uniformly higher than the predicted values. We believe that by providing this as a predicted WBGT correction value, it can be used for on-site heatstroke crisis management.