中国西北地区气象干旱时空演变特征

中国西北地区气候干燥，降水稀少，干旱频发。基于西北地区136个气象站1961-2016年的观测数据，以标准化降水蒸散指数(SPEI)表征气象干旱，采用线性回归、Pettitt突变检验、小波分析等方法对西北地区的气象干旱时空演变特征进行分析。结果表明：西北全区表现为不显著变湿的趋势，从行政分区来看，陕西、宁夏、甘肃均表现为不显著变干趋势，青海的春季、新疆的年和四季均表现为显著变湿趋势；西北全区及其各省(区)气象干旱的突变年份主要集中在20世纪70-90年代，仅青海的春季以及新疆的年和四季通过了显著性检验；西北全区及其各省(区)气象干旱存在3～9、10～15、17～23、25～27 a的主周期；从空间分布来看，西北地区表现为东部变干、西部变湿的趋势。研究结果可为我国西北地区防旱抗旱以及水资源规划等提供依据。

Spatiotemporal evolution characteristics of meteorological droughts in northwest China

The climate regimes in northwest China are dry, with scarce precipitation and frequent droughts. Based on the meteorological observation data of 136 meteorological stations in northwest China from 1961 to 2016, we used the standardized precipitation evapotranspiration index (SPEI) to characterize meteorological droughts, linear regression, Pettitt mutation test, and Morlet wavelet analysis to analyze the evolution characteristics of meteorological droughts in northwest China. The results show that an insignificant wetting trend was shown over the whole study region. From the perspective of administrative divisions, Shaanxi, Gansu Province and Ningxia Autonomous Region showed an insignificant drying trend, whereas Qinghai Province and Xinjiang Autonomous Region showed a significant wetting trend in diverse seasons. The change-point of meteorological droughts in the whole region and individual provinces (autonomous regions) were mainly concentrated in the 1970s-1990s; however, only the spring in Qinghai Province and the year and four seasons in Xinjiang Autonomous Region passed the significance test. The droughts in the whole northwest region and the provinces (autonomous regions) had a major period of 3-9, 10-15, 17-23, and 25-27 years. From a spatial perspective, the northwest region showed a trend of drying in the east and wetting in the west. The results can provide a technical support for drought mitigation and water resources planning in northweat China.