1961-2015年新疆降水及干旱特征分析

基于1961-2015 年新疆地区51 个气象站过去55 a 逐日降水资料，借助标准化降水指数、降水距平百分率表征干旱，利用线性趋势，K-means 聚类，Mann-Kendall 非参数检验，Morlet 小波分析等方法，分析过去55 a 降水及干旱变化特征。研究表明：（1）过去55 a 新疆降水量、雨日整体呈上升趋势，相关系数为0.83，降水量增加主要表现为雨日增长；降水空间分布和聚类得出，降水呈现显著“北多南少”格局，3 个降水分区的降水量表现为III 区 > II 区 > I 区。（2）干旱指数SPI、降水距平Pa极显著相关，干旱频次、影响范围、严重性总体呈现下降趋势；干旱变化率空间分布整体存在一致性，由南向北干旱缓解趋势增大，但局域上又有异质性，北疆个别站点干旱加剧；（3）干旱变化具有周期性，主周期为8 a，次主周期为4 a、16 a。

Precipitation and drought characteristics in Xinjiang during 1961-2015

Drought is a natural phenomenon whose occurrence is linked to a sustained lack of precipitation. When a lack of precipitation causes a substantial hydrological imbalance, there is a drought event. Recently, the consideration of global warming has been paid more attention, the northwest China is very sensitive to the climate change. Therefore, more and more meteorologists are attracted to study droughts. By using linear regression, K-means, Mann-Kendall nonparametric statistical test and Morlet-Wave analysis, the characteristics of precipitation and drought in the target area were analyzed based on long-term(1961-2015)daily precipitation data from 51 meteorological stations. The results show an uptrend on precipitation and rainy days over the past 55 years, and the correlation analysis indicates that the increase rainy day mainly caused the increase in precipitation. Regional precipitation characteristic was obtained by K-means cluster, the precipitation in mountainous area (III cluster)was much higher than that in north Xinjiang(II cluster), and south Xinjiang(I cluster). Also, the relationships between elevation and precipitation in both north and south Xinjiang were analyzed respectively. It revealed only significant correlation in north Xinjiang. Furthermore, correlation analysis shows that SPI and Pa were significantly correlated and there was a downward trend in drought frequency, scope and severity. The spatio-temporal variation of drought relief showed an increasing trend from south to north throughout the target area, but there was some heterogeneity at local scales, drought became more severe at some individual sites in north Xinjiang. Three periodic oscillation of droughts were found, including 4-year period, 8-year period and 16-year period; 8-years period was dominant.