Helicity characteristics of cyclonic vortexes and their effect on convection in a wide‐ranging extreme rainstorm in China

On 20–22 July 2012, a severe rainstorm occurred in the Sichuan basin of Southwest China and Beijing area North China. This was related to activities Tibetan Plateau vortex (TPV) (SWCV). By using radiosonde, satellite brightness temperature, NCEP_FNL data, we investigated helicity characteristics nearly vortexes their effect on convection. Results showed that (1) strong precipitation mainly interaction between TPV SWCV, while northward movement cyclonic caused by split SWCV. (2) During occurrence rainstorm, four mesoscale convection systems (MCSs) were observed. Their vertical structure positive vorticity–negative divergence lower levels, negative vorticity–positive upper accompanied upward movement. an important factor development maintenance MCSs, as well one mechanisms for producing heavy precipitation. this basis, further discussed MCSs atmospheric environment with rotational characteristics. increase water vapour storm-relative more likely cause MCSs.