黄河中上游流域初夏降水变化特征分析

First Month of Summer Precipitation Climate Characteristics in the Upper and Middle Reaches of Yellow River

摘要: 利用黄河中上游45个气象站1961~2011年6月降水资料，采用降水变率、降水距平百分率、线性倾向估计、三年滑动平均等统计方法，分析了近51年黄河中上游地区初夏降水的时空变化规律。结果表明：黄河中上游地区初夏降水具有明显的空间差异，降水量由东南向西北呈递减格局；降水的年际变化从西南向东北呈递增趋势；近51a来流域平均降水以2.45 mm/10a的速率缓慢增多。从1960年代至今经历了“升–降–升–降”两次明显的波动，1970年代后期到1980年代中期明显增多，1980年代后期到1990年代中期明显减少，1990年代后期至本世纪初略有增多，以后又迅速减少。按年代统计表明：1960、1970年代黄河中上游地区初夏处于少雨期，1980年代处于明显多雨期，1990年代略多，本世纪2001年~2011年与历年同期平均持平，接近常年。

Abstract: According to the precipitation data in Yellow River valley from 1961 to 2011 in June, the author analyzes the precipitation change characteristics of the valley in the first month of summer by the variability of precipitation, the precipitation anomaly percentage, linear trend estimation and moving average of 3 years. These data go through 51 years and come from 45 observational stations. The result shows that the precipitation of the first month of summer decreases from the southeast to the northwest, but it increases from the southwest to the northeast. The entire basin average precipitation has slowly increased at a rate of 45 mm/10a in recent 51 years. The area has experienced two obvious fluctuations of “up-down-up-down” from the 1961 up to 2011. The precipitation increased significantly from the late 1970’s to mid 1980’s, but it decreased obviously from the late 1980’s to mid 1990’s. From the late 1990’s to the beginning of this century, the precipitation has slightly increased, and then decreased rapidly. The statistics show that the area had less rainfall from 1960’s to 1970’s, and in the 1980’s it had obvious rainy period but it had slight more rain in 1990’s. The precipitation in the year from 2001 to 2011 was like the corresponding period flat of the past years.