Abstract: The southwest of China has suffered a great drought since 2009. The authors chose five provinces (Yunnan, Guangxi, Sichuan, Chongqing, Guizhou) as the study area, by using the daily precipitation data from 1970 to 2011 of the 126 meteorological stations in the five provinces, the ten-day precipitation variation rates from 2009 to 2011 for the five provinces were calculated. The results indicated that the precipitation variation rates were negative in most time of the three years. The precipitation reduced at those years, and the decrease of precipitation was most serious in the period from October to March, which are the dry season of this area, therefore, such situation exacerbated the drought degree. The drought had some rules in the spatial distribution that the drought often happened from the Guangxi province first, and then spreaded to the Yunnan and Sichuan provinces, and the drought also ended from the Guangxi province. In addition, through the regress analysis, it was found that the precipitation of the five provinces was influenced by the West Pacific subtropical high and the Tibet plateau barometric pressure, and the effects of the different circulation parameters on the precipitation were not the same.

Key words: southwest of China, drought, precipitation variation rate, atmosphere circulation parameter

摘要： 针对2009年开始的我国西南地区大旱, 选择云南、广西、四川、重庆、贵州5个省份作为研究区域, 利用西南五省126个气象站1970-2011年逐日降水数据, 计算并分析西南五省2009-2011年逐旬的降水变率情况。结果表明这3年中西南五省大部分时间降水变率都为负, 即降水量比往年少, 而且从10月至来年3月是降水量减少最严重的时期, 这几个月正好是西南地区的干季, 干季更干的状况加剧了此次旱灾的危害程度。旱情的发生在空间分布上有一些规律, 基本上都是广西先出现旱情, 然后扩展到云南、四川, 结束时也是广西首先得到缓解。此外, 通过环流参数相关分析, 发现西南五省降水受到西太平洋副高以及西藏高原气压场的影响, 不同的环流参数影响的地区和时间不尽相同。

关键词: 西南地区, 干旱, 降水变率, 大气环流参数