A Statistical Study of Wind Gusts in Japan Using In Situ Surface Observations

Wind gusts in Japan were statistically examined using meteorological data recorded by 151 surface stations of Japan Meteorological Agency from 2002 to 2015. The surface weather stations are deployed all over Japan, including isolated island areas. The wind gust is defined by the following conditions; 1) 3-sec mean wind speed must be at least 15 m/s faster than the pre-10-minute mean wind. 2) 3-sec mean wind speed must be at least 10 m/s faster than the post-10-minute mean wind. 3) 3-sec mean wind speed must be at least 10 m/s faster than the maximum 3-sec wind speed averaged over pre-3-minute.

As a result, as much as 3518 events were extracted as wind gusts, and 57 % of them occurred within 800 km radius from the tropical cyclone center. The frequency of wind gusts averaged over all stations is 0.90 day per year, which is much higher than expected. The coastal regions and island areas have a higher frequency of wind gust occurrence.

 Wind gusts associated with tropical cyclones occur most frequently in September, and most of them occur in the right-front quadrant of tropical cyclone within a radius of 400 km from the tropical cyclone center. The southern part of Japan has a high frequency of them. In the meanwhile, wind gusts without tropical cyclones occur most frequently in December, and the northern and eastern parts of Japan have a high frequency.