关键词: 我国副热带, 气候分布, 深对流, 日变化

Abstract: Due to the finer temporal and spatial resolution and the better integrality of long-term satellite infrared (IR) temperature of black body (TBB) data, a climatology of deep convection over the subtropics of China( 94 °-124 °E, 24 °-36°N) during summer is presented based on the 1-hourly IR TBB data during June to August of 1996-2007 (2004 excluded). The results show that the climatological characteristics of deep convection denoted by TBB≤ - 52℃ over the subtropics of China are basically consistent with those previous statistical studies based on the surface thunderstorm observations and the low-orbit satellite lightning observations. The monthly variations, pentad variations and diurnal variations of the deep convection over the subtropics of China are focused on. The results show that there are 3 active deep convection areas in the subtropics of China during the period of June-August: Plateaus of Western Sichuan, northeast Yunnan-Guizhou Plateaus, and Zhejiang-Fujian-Jiangxi areas. The monthly variations of the deep convection over the subtropics of China are closely associated with the East Asia Monsoon and the large-scale atmospheric circulation. The deep convection is more active in June and July than in August. The development of the deep convection over the subtropics of China has a characteristic of intermittence, and the active pentad period of the deep convection over the Yangtze-Huaihe River Basin clearly reflects the rainfall events during the Meiyu period and the secondary Meiyu period. The diurnal evolution of the deep convection shows that the deep convection over the Plateaus of Western Sichuan propagates southeastwards after sunset, and then propagates northeastwards to the east Sichuan Basin after midnight, the deep convection over the northeast Yunnan-Guizhou Plateaus propagates southeastwards to north Guangxi after sunset, and the deep convection over Zhejiang-Fujian areas extends westwards and northwards at sunset and retreats eastwards and southwards after sunset. This characteristic of the diurnal variations of the deep convection is, to a great extent, determined by the local topographic distribution. The diurnal variations of the deep convection over the subtropics of China also show that there are two types of diurnal variations of deep convection: single-peak convection and double-peak convection. The diurnal variations of the deep convection over Plateaus of Western Sichuan, Yunnan-Guizhou Plateaus, and Zhej iang-Fujian areas have one peak, but the active period over Plateaus of Western Sichuan and Yunnan-Guizhou Plateaus is much longer than that over Zhejiang-Fujian areas, and the frequency of the deep convection over Yunnan-Guizhou Plateaus in the active period changes much slower than that over the other two areas. The diurnal variations of the deep convection over eastern Sichuan Basin, the Yangtze-Huaihe River Basin, Hunan and Guangxi have two peaks, but the main deep convection peak over eastern Sichuan Basin is before sunrise ( 22UTC) and different from that over the other 3 areas at sunset (09-10 UTC) , and the amplitude of the diurnal deep convection variation over the Yangtze-Huaihe River Basin is much smaller than that over the other 3 areas.

Key words: subtropics of China, climatology, deep convection, diurnal variations