| Meteorological conditions have direct and obvious effect on spacecrafts' launch, such as artificial satellites. It's the meso-scale strong convective weather(SCW for short afterwards) which is the difficulty and emphases of meteorological support in XiChang Satellite Launch Site (XSLS for short), especially the thunder weather. XSLS lies at southeast of the Tibetan Pleateau and east of Hengduan mountains, where the particular position and topography surrounding result in SCW with characteristics of not only outburst, complexity and occur at local area, but also happened at every months of the year and with very strong thunder, which is the main factor to restrict the periods of usable launch time in XSLS. Based on the climatic statistics and analysis of SCW that affected the launch missions of XSLS, using kinds of conventional and unconventional data, two cases of SCW which seriously affected the launch missions are investigated by analysis of macro-scale surrounding, meso-scale structure, numerical simulations of surface heating effect and meso-scale mountains' dynamic effect.The research proved that the SCW of XSLS with obvious differences in dry season and rainy season and distinctly changed with day time, are mainly affected by southwest vortex and shear in the rainy season and by cold air from Sichuan basin and cold fronts in other seasons. There is a local property of SCW in Anning valley which XSLS lies at that it was developed from north to south. The weather systems which directly cause the SCW are meso-P vortex and shear at east of Hengduan mountains and there are comparatively strong cold front at about 30°N. The SCW in rainy season and its about with big precipitation and longer duration are mainly happened at warm-moisture mass near subtropical high and the vapor from Sichuan basin and peninsula of central-southern China led the obviously increase of lower-level humidity near XSLS, and resulted in fell of the levels of ascending and free convective condensation to generate the rapidly development of CAPE which caused the unstable stratification and accumulated energy, and the frontogenesis induced by cold air near low level at XSLS is a triggering mechanism. The SCW in other seasons are with small precipitation, shorter duration, but nearly same strong thunder, whose macro-scale surrounding were mainly formed by strengthening and west-forwarding of the southwest quasi-stationary front conduced by NE cold air and the meso-P southeast brink front of the Tibetan Plateau caused by NW cold air and local topography directly caused the thunderstorm, so formed the unique "two-fronts" pattern to cause SCW of XSLS. A series of sensitivity experiments proved that the geographic thermal forcing, both including the sensible and latent flux played important roles in the cases, especially at the beginning that with almost the same quantities, which is obviously different with rainstorms of the Yangtse-Huaihe river district and south China where the latent flux are most important. They played the partes by causing the instable stratification and favorable backgrounds for meso-scale systems. Among the meso-scale mountains near XSLS, the northwestern and northern topography enhanced the precipitation of the valley, the eastern mountains mainly affected the SCW by blocking off the NE flow, and the southwestern and southern topography worked on by mainly affecting the vapor transportation to reduced the precipitation and obviously affected by the directions of the vapor. The mesoscale topography have significant actions by effect on the flows to transport substances and energy, and on development of meso-P systems, furthermore directly acted as triggering mechanisms, so it's maybe one of the key factors for SCW in XSLS and its about.
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