Estimation of WBGT with JMA products and information web site for heat stroke in Japan

In Japan, WBGT (Wet-bulb Globe Temperature) is widely used as the index for heat stroke. In order to estimate WBGT, we have to observe temperature, humidity and globe temperature. However, globe temperature is not observed at general observatories. To provide public information to evaluate risks for heat stroke, we estimate WBGT with experimental equations from parameters generally observed, i.e. temperature, humidity, sun radiation (or sun duration) and wind speed. The bias of equations with sun radiation is -0.2 to +0,4 degree in Celsius and standard deviation is 0.4 degree for 2010 summer. In case of estimation with sun duration, the bias is -0.3 to +0.4 degree, and standard deviation is 0.5 degree. Additionally we estimate WBGT from re-analysis data issued by JMA. The bias of such estimation is +0.3 to +1.2 degree and standard deviation is 1.5 degree. In 2010 summer season, we experimentally provide observed/estimated WBGT values at 47 major cities in Japan with WBGT forecasts for same cities on the web site (http://www.nies.go.jp/health/HeatStroke/). The web site informs people of actual/future/past condition for heat, and it contributes people to reduce exposure risks for heat.