Current Issue

28 August 2010, Volume 29 Issue 4   
  • A Case Study on Plateau Vortex Inducing SouthwestVortex and Producing Extremely Heavy Rain
  • 2010 Vol. 29 (4): 819-831. 
  • Abstract ( ) PDF (1709KB) ( )
  • Using the multiple detections, observationsand reanalysis data, it is analyzed a weather process where a Plateau Vortex moved eastward, induced a southwest vortex and produced extremely heavy rainstorm on 20~21 July 2008 by diagnostic analysis, numerical simulation and sensitivity experiment. Then it is investigated the mesoscale environmentalfeatures during the extremely heavy rainstorm, the role of particular topography and diabatic processes in the development, eastward movement, south\|west vortex inducing and extremely heavy rainstorm producing of the Plateau Vortex. The results show that the Plateau Vortex moved downward along the northeast side of Tibetan Plateau and induced a south\|west vortex in Sichuan basin after its formation. The extremely heavy rainstorm in the middle of Sichuan Province is resulted from severe mesoscale convective systems (MCSs) triggered in the formation of southwest vortex. The easterly winds induced by Plateau Vortex are forced to release convective available potential energy, trigger MCSs and produce intensive heavy rainstorm under the dynamic lifting of the topography in the east of Chuanxi Plateau. The condensation latent heating of precipitation drives the fast development of the southwest vortex. Only formed is a shallow southwest vortex under the dynamic role of the topography. The southwest vortex is sufficiently developed only when the rainfall condensation latent heating is feedback. The development of the Plateau Vortex, which determines the south\|west vortex growth to a large degree, is mainly influenced by the surface heat flux. The high mountains around Sichuan basin exert a different influence on the position of southwest vortex respectively, while the micro\| and mesoscale peaks embedded on the high mountains do not greatly affect the position of southwest vortex and heavy rain band, but the rainstorm dropping zone to a certain degree.