Abstract:

Based on meteorological observational data,NCEP reanalysis data and cloud pictures of FY2C,the occurring and developing mechanism of a MCC event on Nov. 9,2010 was analyzed. The results show that the MCC occurred in a ground warm inverted trough.The moving eastward of a low trough at 500 hpa,the development and moving eastward of a low vortex at 850 hpa and the weak cold front caused by the moving southward of the cold air on the boundary layer provided favorable environmental conditions for the formation of MCC.The MCC occurred in the convective unstable area where the low energy tongue in the middle troposphere overlapped with the high energy tongue in the lower troposphere.Upperlevel divergence, low level convergence and the coupling of the strong vorticity column and divergence column was the main dynamical mechanism of the MCC development and maintenance.During the developing and mature stage of the MCC,the atmosphere was unstable layer which strengthened with the rainfall and appeared the feature of wet neutral vertical motion in the middle and lower troposphere levels.In the mature stage, the wind direction in the MCC center with strong wind shear shifted clockwise with the height and the MCC had the structural characteristics of supercell storm