2007 年 32 巻 1 号 p. 21-28
The detailed structure of a gustfront was revealed with Doppler radar, Doppler sodar, weather station and video cameras at Yokosuka observation site, Japan. The gustfront was accompanied with a downburst from bow echo of developing thunderstorm. Two gusts occurred at the passage of gustfront. First gust was observed about 2 km behind the gustfront. Second gust occurred about 5 km behind of the first gust and maximum wind speed of the second gust was larger than that of the first gust. The vertical circulation of the gustfront had about 5 km in horizontal scale and 500 m in vertical and made "arc cloud" , which had 200m of cloud base and 500m of cloud top in height. Strong wind cores (> 25 m/s) existed between 30 m and 500 m in height at the front of the circulation. Two gust winds, which were observed at the surface, were well corresponded with the strong wind core near the surface and updraft region of the circulations. Vertical distribution of the wind speed changed remarkably for 5 minutes in the vertical circulations.