基于SPEI的西南地区近53 a干旱时空特征分析

论文基于标准化降水蒸散指数（SPEI），统计分析西南地区128 个测站1960-2012 年的气象数据，从干旱年际变化趋势、四季变化趋势、干旱强度、干旱事件频次、干旱频率以及与ENSO的关系，对西南地区近半个世纪的干旱时空特征进行了分析。结果表明：①西南地区及子区域近53 a 来呈干旱化趋势，21 世纪初干旱发生最频繁，干旱强度、极端干旱及中等干旱的频次均呈增加趋势；②四季大部分区域呈干旱化趋势，以秋季最为突出；③春季，干旱发生频率最高且集中在横断山地、四川盆地东部和云贵高原中部，夏季，横断山地北部、若尔盖高原和广西丘陵西北部易发生干旱，秋季，云贵高原、广西丘陵及四川盆地部分区域干旱频率较高，冬季，干旱易发区集中在若尔盖高原、四川盆地西南部一线；④各区域四季的干旱指数与ENSO指数相关性不同，并且ENSO事件强度与四川盆地和横断山地的SPEI 在年变化趋势方面存在明显负相关，与其他区域呈正相关。此外，西南地区在厄尔尼诺年和拉尼娜年都会出现干旱，但前者爆发干旱灾害的概率比后者高。而且各区域存在差异，四川盆地、若尔盖高原在厄尔尼诺年易发生干旱，而云贵高原在拉尼娜年发生频率较高，广西丘陵、横断山地没有明显规律和特征。

Temporal and Spatial Distributions of Drought in Southwest China over the Past 53 years Based on Standardized Precipitation Evapotranspiration Index

Based on Standardized Precipitation Evapotranspiration Index (SPEI), this study statistically analyzed the meteorological data of 128 meteorological stations during 1960-2012 in Southwest China. It analyzed temporal variation characteristics of drought in nearly half a century from the following perspectives: annual variation trends of drought, seasonal variation trends of drought, drought intensity, the frequency of drought events, drought frequency as well as the relationship with ENSO events. The results show that: 1) It tends to be dry in the entire region of Southwest China and other sub-regions in the past 53 years, and the drought occurs most frequently at the turn of the century. The drought intensity also tends to increase, so does the frequency of extreme drought and medium drought. 2) Most parts of the region tend to be dry in all seasons, it is especially typical in autumn. 3) In Southwest China, the drought happens most frequently in spring, which mainly distributes in Hengduan Mountains, the east Sichuan Basin and the central Yunnan-Guizhou Plateau. In summer, drought mainly distributes in the north Hengduan Mountains, Zoige Plateau and the northwest Guangxi hilly area. In autumn, the drought often happens in Yunnan-Guizhou Plateau, Guangxi hilly area and some parts of Sichuan Basin. In winter, the drought mainly happens in the Zoige Plateau and southwestern part of Sichuan Basin. 4) There are different relevances between the seasonal drought index and ENSO index in all the sub-regions. In the aspect of annual variation trend, there is a significantly negative correlation between the ENSO strength and SPEI of the Sichuan Basin and Hengduan Mountains, and other areas are the opposite. Meanwhile, the droughts will occur in the El Niño and La Niña year in Southwest China. But the drought frequency is higher in the year when the the El Niño events occur than the La Niña events do. However, there are regional differences, it is in El Niño years that the drought often happens in the Sichuan Basin and Zoige Plateau, while Yunnan-Guizhou Plateau is opposite and Guangxi hilly area and Hengduan Mountains are inconspicuous.