近百年西南地区干旱的多时间尺度演变特征
Characteristics of Multi-timescale Variabilities of the Drought over Last 100 Years in Southwest China
中文摘要：
以干旱变化的不同时间尺度特征为出发点，利用具有多时间尺度变化并考虑温度影响的标准化降水蒸散指数（Standardized Precipitation Evapotranspiration Index，SPEI）对我国西南地区近百年的干旱演变特征进行了分析。通过与年鉴资料对比，证明SPEI指数在西南地区具有较好的适用性。进一步分析表明，长时间尺度的SPEI指数具有年代际变化特征，分别在1940年前后和2006年8月达到近百年来的最低值；而短时间尺度的SPEI具有季节和年际振荡的特征。不同时间尺度的干旱叠加会导致极端干旱事件发生，从而对社会经济造成严重影响，比如2006年夏季的川渝高温干旱。相对而言，1972年我国西南地区虽然也发生了伏旱灾害，但由于没有多时间尺度干旱叠加，旱灾就不严重。针对近百年温度变化对西南干旱影响的分析表明，高温对干旱的贡献也不可忽视，常常可以达到20%～25%。
中文关键词：
多时间尺度，SPEI指数，西南干旱
KeyWords：
multiple time scales, SPEI, the drought in Southwest China
Abstract：
The characteristics of 20th drought in Southwest China at different time scales have been investigated based on SPEI (Standardized Precipitation Evaportranspiration Index), which is a multi-timescale drought index and takes temperature into account. Firstly, in comparison with observations, the SPEI is confirmed to be applicable to analyze the drought in Southwest China. Secondly, the results present that at longer time scales the SPEI have a feature of interdecadal variability with minimum values of SPEI appearing around 1940 and in August, 2006. In contrast, the temporal evolutions at shorter time scales of the SPEI are characterized by seasonal to interannual oscillations. Sometimes, the droughts at different time scales may happen simultaneously, which may produce extreme drought events affecting society and economy seriously (for instance, the summer drought in 2006 in Sichuan and Chongqing). However, compared with the summer drought in 2006, the summer drought in 1972 is not that severe because there is no overlap of droughts at different time scales. Finally, the contribution of temperature anomaly to the drought is also analyzed. The result indicates that high temperature contribution cannot be neglected and its probability can reach as high as 20%-25%.