Mesoscale and local‐scale climatology of extreme temperature events in Niigata, Japan

Abstract

AbstractIn this study, we analysed the characteristics of extreme temperature events (ETEs) that occurred in Niigata City, located in the coastal region of the Sea of Japan. The results show that there was a tropical cyclone (TC) in the vicinity of Japan (in the latitude range of 29.0°–45.8°N and longitude range of 123.2°–139.2°E) on 60% of the days when ETEs occurred in Niigata City (TOP10 days in the past 30 years, 0.09 percentile). Furthermore, the strong east‐southeast to southeast winds caused by the TCs and winds over the mountains reached Niigata City. These results indicate that ETEs in Niigata City are caused by southeasterly foehn winds associated with TCs. It is generally believed that ETEs in Niigata City increase the risk of heatstroke. However, the index for heatstroke risk level is not high despite the extreme temperatures. This is because the downslope winds from the mountains become strong, and humidity decreases during the ETE event. A comparison of the results of this study with those of previous studies shows that the favourable atmospheric conditions for the ETE event and the impact of the ETE on local weather and human life differ greatly between the Pacific and Sea of Japan coasts.