INFLUENCE OF TYPHOON IN THE EAST CHINA SEA ON THE SOUTHWEST VORTEX RAINSTORM IN SICHUAN PROVINCE

LEI Li-juan; LEI Xiao-tu

doi:10.16032/j.issn.1004-4965.2018.03.004

Abstract：Using NCEP 6-hourly reanalysis data、the hourly rain data and the mesoscale numerical model WRF, the southwest vortex rainstorm (SVR) occurred in the eastern part of Sichuan province from 5th September, 2010, 14pm (UTC+8) to 6th, 20pm is diagnostically analyzed and numerically simulated.Intensive discussions are made about the impact of typhoon in the East China Sea on movement and maintenance of the southwest vortex and the transportation of water vapor. The results show as follows.(1) The SVR in eastern Sichuan province was formed under favorable conditions.Such as the circulation background of "two troughs and one ridge" in the mid-latitude 30～50 °N,the eastward moving low system (southwest vortex) of the western plateau of Sichuan province was indirectly blocked by the northward typhoon in the East China Sea,and the water vapor from the South China Sea and the bay of Bengal was continuously transported to the storm area. (2) Typhoon"Malou"did not transport water vapor to the southwest vortex rainstorm area. (3) The typhoon in the East China Sea had a "blocking" effect on the moving eastward southwest vortex: the speed of Eastward system (including southwest vortex) in westerlies upstream slowed down because of the effect of typhoon,and prolonging the "retention" time of southwest vortex in the eastern part of Sichuan province, which played an important role in causing the heavy rainfall in the region.