Structure of a waterspout occured over Tokyo Bay on May 31, 2007

Abstract

On May 31, 2007, a waterspout occurred over Tokyo Bay near the Futtsu Coast, Chiba Prefecture, Japan. Based on Doppler radar observations and the field surveys, the detailed structures of the funnel and the parent cloud were revealed. The funnel diameter was about 25 m near the surface, and expanded as the altitude increased. The misocyclone had a diameter of 0.2 km and vorticity on the order of 10-1 s-1 below the cloud base. The lifetime of the funnel was about 7 minutes, while that of misocyclone was about 20 minutes. The waterspout formed over the wind shear zone, which was favorable for the formation of an anticyclonic vortex.