乌鲁木齐河流域降水量时空变化特征

摘要

Based on the monthly precipitation data of seven meteorological stations in Urumqi River basin from 1961 to 2009,the spatio-temporal variation characteristics of annual precipitation were analyzed by using linear regression,climatic inclination rate and abrupt change detection methods. The main results are as follows:The were obvious vertical differentiation of precipitation in Urumqi River basin, the average value of annual precipitation is a parabola tendency with the sea level elevation. The most annual precipitation occurs at altitude of 1900 to 2600 m, and the most precipitation is 520 mm to 550 mm correspondly. The change of monthly precipitation in a year is a single peak type,the precipitation from October to March is less than that of April to September, the precipitation in the upper reaches is more than that in lower reaches. The average annual precipitation was increased by the change rate of 14. 417 mm/(10a), and the change rate of annual precipitation was increased with sea level elevation in Urumqi River basin. Abrupt examination indicated that, the annual precipitation was increased abruptly in 1992 after which the mean precipitation after 1992 is more than that before 1992 by 14. 5 ％. The variation coefficient of annual precipitation is decreased with sea level elevations. Annual precipitation has the periodic variation by the different time scales of quasi-3a, 6a and 8a in Urumqi River basin.%根据乌鲁木齐河流域7个气象站1961-2009年逐月降水量资料,使用线性回归、气候倾向率、MannKendall突变检测、Morlet小波等方法,分析了流域内年降水量的时空变化特征.结果表明,乌鲁木齐河流域降水量的垂直分异十分明显,从古尔班通古特沙漠南缘的河流末端到天山一号冰川的河源地带,年降水量的多年平均值随海拔高度总体呈抛物线型,年最大降水量出现在海拔1 900～2 600 m的中山带,对应的最大降水量约为520～550 mm;流域内各地降水量的年内分布均为单峰型,冬半年(10月至翌年3月)各月降水较少且各站点的降水量差异很小,夏半年(4月至9月)各月降水较多并且上游区域降水量远多于中下游区域;49 a来,流域各站的年降水量均为增多趋势,降水增多倾向率随海拔高度呈线性递增趋势,全流域平均年降水量递增倾向率为14.417 mm/(10a);突变检测表明,乌鲁木齐河流域年降水量于1992年发生了显著的突变性增多,突变后降水量较突变前平均增多了45 mm,增多14.5%;乌鲁木齐河流域年降水量的不稳定性(变异系数)随海拔高度呈显著的幂函数型递减趋势,海拔越高的区域降水的年际间稳定性越好,反之亦然;乌鲁木齐河流域年降水量具有准3 a、准6 a和准8 a的周期变化.