Distribution and Spatiotemporal Variations of Deep Convection over China and Its Vicinity During the Summer of 2007

The large-scale persisting rainstorm, extremely heavy precipitation and severe convective events result in tremendous damage in economy and severe personnel casualty during the summer of 2007. Based on FY-2C hourly infrared T_BB dataset from June to August in 2007, the distribution and spatiotemporal variations of deep convection over China and its vicinity during the summer of 2007 is analyzed and compared with the atmospheric circulation background based on the NCEP final analysis dataset and the climatological distribution of deep convection based on 10-year T_BB dataset. The statistical characteristics of T_BB less than -52℃ show that there are four active deep convection areas over China during the summer of 2007: South China seaside, the Tibetan Plateau, the Yunan-Guizhou Plateau, Sichuan Province together with Chongqing City and the Yangtze-Huaihe River Basin. The daily variations of deep convection over Central and East China show that the deep convection distribution is very different in different months, and the deep convection activity has an obviously fluctuating feature. The active deep convection areas are farther south and are located to the south of 30°N in June, and the active deep convection areas advance to the north of 40°N in July, however, the active deep convection areas retreat to the south of 25°N in August. The characteristics of the daily variations of deep convection are close associated with the evolution of the large-scale atmospheric circulation. The deep convection over the Tibetan Plateau and the Yunnan-Guizhou Plateau has one active peak and lasts longer time in the diurnal variations, but the deep convection over the Sichuan Basin and Chongqing City has a nocturnal characteristic and develops in the early morning. Comparing with the 10-year statistical results of T_BB less than -52 ℃, there are some characteristics different from the 10-year results. First, the deep convection over South China occurrs more frequently in the afternoon than those in the 10-year statistical results. Second, the lifetime of the deep convection over Tibetan Plateau is much shorter than the climatological lifetime. Third, there are multiple active periods of the deep convection in a day over East Guizhou Province, the Northeastern Mountains in Sichuan Province, the Western mountains in Hubei Province, the Hills in Shandong Procince, the Yangtze-Huaihe River Basin, and the Plain of North China. Finally, there is feature of the deep convection over the Yangtze-Huaihe River Basin that the deep convection obviously propagates eastward during the summer of 2007.