08.6广西连续暴雨的大尺度环流和物理条件分析

Analysis on Physical Condition and Macro scale Circulation of "08.6" Successive Torrential Rain in Guangxi

利用常规观测资料、自动站资料和每6h一次的NCEP1×1分析资料,对2008年6月8日～18日广西连续暴雨过程的大尺度环流和物理条件进行了分析。结果表明:副热带高空急流右侧维持强辐散场,500hPa中、低纬广西维持低压槽区,中、高纬东亚大槽和其后部阻塞高压形势维持,贝加尔湖以西宽广的槽区不断有小槽分裂东移,低空西南急流不断为暴雨区提供了大量的水汽和不稳定能量,是本次连续性暴雨过程产生的有利大尺度环境背景;连续暴雨由3次连续高空槽引导低层低涡切变东移产生,由3个加强期和2个减弱期组成,暴雨的增强和减弱受暴雨区大气动力、热力、水汽条件变化的影响,高空辐散和低空辐合耦合增强、垂直上升速度增大、低层水汽的辐合、不稳定能量累积,强降水发展加强,反之,强降水减弱。

Based on the regular observed data, automatic station data and NCEP1×1, physical condition and macro scale circulation of successive torrential result shows that： right of subtropical high level jet rain, which occurred in 8th-18th June, 2008. The maintain a strong divergence field. On the 500 hPa level, at mid-low latitude regions of Guangxi had a rough. At mid-high latitude, the Eastern Asia Trough maintained, the Trough＇s hind side had a blocking high, small trough was endlessly spitted from the broad trough at western of Baikal. Low-level southwest jet supplied large moisture and instability energy to the placement of rainfall. Those are the favorable large scale environmental setting of successive torrential rain; the successive torrential rain was resulted from three times of upper trough guided underlying bed low whorl moved east, there were three strengthen and two weaken periods. The enhancement and weakness of heavy rain were influenced by the changes of heat, water vapor atmospheric dynamic conditions in the heavy rains area. The strengthenment of upper divergent, the lower convergence coupling, rise of vertical speed, convergence of the lower water vapor and accumulation of unstable energy would all lead to the stronger precipitation. Conversely, the rainfall is weakened.