ON THE MESOSCALE DEPRESSION IN LARGE-AREA SEVERE CONVECTION EVENTS OVER ZHEJIANG

The use of the band-pass filter is made to analyze the rnesoscale systems in large-area:severe convection events over Zhejiang.It is found that all cases analyzed are closely related to the mesoscale surface depressions.The outbreak of severe convection in the depression is derectly related to the moisture convergence and the asending motion in the boundary layer.Most of hailfalls occur in the convergence center.