A Comparative Experimental Study of an Extreme Rainstorm Caused by the Southwest China Vortex during the Intensive Observation Period

Abstract A rainstorm caused by the Southwest China vortex (SWCV) in Sichuan during 7 July–10 July 2012 is analyzed by using the NCEP data of 1º×1º with 6-hour interval, the conventional observed data and the intensive observed data of SWCV experiment during flood season. The results show that using the Southwest Center – WRF ADAS Real-time Modeling System (SWCWARMS), compared with the control experiment, the distribution of rainfall in assimilation experiment is more similar with the actual precipitation. By assimilating intensive observed data, the southerly flow exists in northern Sichuan in initial time, which benefits for the newborn of SWCV. Contrast research shows the strength and the range of SWCV are much larger than them in control experiment. In addition, there is a phenomenon that airflow heaps up at the south side of Daba Mountain due to the blocking function of terrain, which causes rainstorm at the border of Sichuan and Shanxi. So, assimilating the intensive observed data in regional modeling system can improve the weather forecast of heavy rainfall and promote the predict ability of SWCV. Key words: Intensive observation, Southwest China vortex, Rainstorm