Comparative analysis between cold front thunderstorm and gale in spring at Shenyang Taoxian international airport

On the basis of the evolvement of spring thunderstorms at Shenyang Taoxian international airport from 1996 to 2005,four typical cases of cold front thunderstorm were analyzed with a combination method.The results showed that the development and strengthen of instability stratification in Shenyang area resulted from warm advection of Mongolia cyclone foreside,large positive vorticity region and positive vorticity advection.Upper divergence and lower convergence provided together the dynamic lifting condition for thunderstorm weather and its strengthens.The upper level dry and cold air with high moist potential vorticity value was superposed to the low-level disturbance,which was advantageous to instability stratification strength and precipitation.Compared with four gale cases in spring without thunderstorms under similar circumstances,the result showed the extended direction of cold front and different distributions of thick divergence layer and low moist potential vorticity over Shenyang may be the main causes for thunderstorms and gales.