Clarification of localized structure in gust hazard from the viewpoint of turbulent organzied motion

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Traveling microbursts were reproduced by dropping dense solution in a water tank. The velocity fields of them were measured through a DPIV method. Mean velocity trace of the simulated microbursts was similar to that of actual them. Turbulence intensity was only 10 % of the peak velocity. The horizontal velocity fields of gust front realized in the multifan wind tunnel were almost uniform. These facts show that localized wind hazards do not occur due to the turbulent fluctuation in atmospheric boundary layer. We found that the localized wind gust appeared when the downdraft was not disturbed by surrounding vortices and concentrated. The simulated localized wind gust was found to correspond to be 30 m/s in the actual microburst whose mean velocity is 16 m/s.