1961—2009年中国区域干旱状况的时空变化特征

Spatiotemporal Characteristics of Drought over China during 1961-2009

利用1961—2009年中国589个气象站月降水和月平均气温资料,采用经验正交函数(EOF)/旋转经验正交函数(REOF)、小波变换及Mann-Kendall突变检验等方法,对年标准化干旱指数的空间异常特征和时间变化规律进行了研究。中国前10个主要干旱异常区为:河套-华北、长江中下游、华南地区、东北大部、陕西南部-青海东部、滇黔-广西丘陵地区、新疆北部、川西高原-青藏高原东部地区、辽东及山东-河南东北部。有7个区域呈现干旱化趋势,其中干旱化最明显的区域为滇黔-广西丘陵地区,其次为河套-华北地区。新疆北部、川西高原-青藏高原东部地区和长江中下游地区呈现变湿趋势,其中变湿最显著的区域为新疆北部。选择变干和变湿最典型的区域进行突变分析。滇黔-广西丘陵区突变发生在1980年前后,新疆北部突变点也出现在1980年前后。小波能量谱显示,中国区域干旱化变化存在多时间尺度特征,2～4a左右的时间尺度的周期振荡最显著。小波谱分析结果表明,中国区域干旱化主要存在3a左右的显著主周期,其中陕西南部-青海东部还存在显著8a和22a主周期。

Based on the data of monthly precipitation and monthly average temperature of 589 meteorological stations over China from 1961 to 2009,the spatial anomaly and temporal evolution characteristics of annual standard drought index are studied by using EOF,REOF,Wavelet analysis and Mann-Kendall test.Main results have been shown as follows.Abnormality of the annual standard drought index over China was significant in ten areas,just as Hetao northern China,middle and lower reaches of Yangtze River,southern China,main part of northeast China,southern Shaanxi eastern Qinghai,Yunnan-Guizhou-Guangxi hilly area,northern Xinjiang,western Sichuan eastern Tibet Plateau,eastern Liaoning,and Shandong northeastern Henan.Among them,the climate became significantly dryer in seven regions and it became significantly wetter in 3 regions.The most significantly drying region was Yunnan-Guizhou-Guangxi hilly area and the most significantly wetting region was northern Xinjiang.The abrupt change took place in 1980 in Yunnan-Guizhou-Guangxi hilly area,and the abrupt change also took place in 1980 in northern Xinjiang for arid-wet change.There existed multiple time scale features over China for arid-wet change according to wavelet energy spectrum,and the fluctuation period of 2～4 years was the most significant.The main period was 3 years over China,and there were main periods of 22 years and 8 years in southern Shaanxi eastern Qinghai for arid-wet change.