On the mesoscale depression in large-area severe convection events over Zhejiang

The band-pass filter is used to analyze the mesoscale 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 directly related to the moisture convergence and the asending motion in the boundary layer. Most hailfalls occur in the convergence center.