1956—2016年中国年降水量及其年内分配演变特征

Evolution characteristics of the interannual and intra-annual precipitation in China from 1956 to 2016

为分析中国降水时空演变格局,本文在月尺度上对水利部门与国家基本气象站的降水量监测数据进行融合,针对融合后的4177个站点,使用趋势分析、突变检验和年内分配向量法等方法分析了集中度、集中期和最大4个月累积降水量占全年之比等多个指数的分布格局,分析了1956—2016年中国年降水系列的趋势性和突变性特征,以及降水年内分配过程的时空演变。主要结论如下:①中国降水时空分布不均,自东南到西北,年降水量总体递减,降水年内分布集中度递增;站点年降水量序列的变化趋势呈现较强的地带性,自东南到西北呈“增—减—增”的3个条带;显著增加条带分别位于东南和西部地区,显著减少的条带位于中部,从东北地区向西南绵延至边境;年降水序列的趋势性变化大多伴随着突变,发生在20世纪80年代的站点最多。②沿200 mm和400 mm年降水量等值线,中国北方出现1个“汛期降水减少”条带,但其时间尺度效应较强;在月尺度上,站点汛期降水占比下降,非汛期降水占比增加;而在日尺度上则相反,连续3~7 d累积降水量的波幅加大,表明降水事件的极端程度在增强。③降水序列变化与径流的同步性较好,中国西北和东南地区年降水量呈增加趋势,典型水文站的还原径流量同步增加;年降水量显著减少、且最大4个月累积降水量占比指数减少超过10%的区域集中在北方的辽河、海河与黄河流域等非湿润区,相应水文断面的还原径流量显著减少。

To analyze the spatio-temporal distribution pattern of precipitation in China,the trend and mutation characteristics of the annual precipitation,as well as the temporal and spatial evolution of the intra-annual distribution,are summarized and analyzed using multiple methods based on the fused monthly precipitation monitoring data of the water conservancy department and the meteorological department of 4177 stations from 1956 to 2016.These methods include the Mann-Kendall test,PETTITT test,and vector algorithm for intra-annual distribution,which explores the distribution pattern of several indices,including the precipitation-concentration degree,precipitation-concentration period,and the proportion indices of the maximum accumulated precipitation in four months to one year.The following conclusions are drawn:①The temporal and spatial distribution of precipitation across China is not uniform.In general,the annual precipitation decreases,and the concentration of annual precipitation distribution increases from southeast to northwest;the changing trend of the annual precipitation at the stations shows a strong zonality with three bands of“increase-decrease-increase”from the southeast to the northwest;the bands showing a significant increase are located in the Southeast and Western China,and the bands showing a significant decrease are located in the central region,stretching from the northeast to the southwest to the border;and abrupt changes are often accompanied with the trend changes of the annual precipitation,of which most sites occur in the 1980s.②Along the 200 and 400 mm annual precipitation contours,one band shows“flood season precipitation reduction”with strong temporal variation in North China.On the monthly scale,the proportion of precipitation in the flood season of the station decreases,and it increases in the non-flood season,while the opposite is true on the daily scale.The amplitude of accumulated precipitation for 3—7 consecutive days increases,suggesting that the extreme degree of precipitation events is increasing.③The changes in the precipitation series and the changes in the runoff series are well synchronized.The annual precipitation in Northwest and Southeast China shows an increasing trend,and the statistical discharge of the typical hydrological stations increases synchronously.However,the stations at which the annual precipitation decreases significantly and where the proportion indices of the maximum accumulated precipitation in four months to one year declines more than 10%,are concentrated in the non-humid areas of Northern China,such as the Liaohe River basin,Haihe River basin,and Yellow River basin.In these regions,the statistical discharge of the hydrological stations has decreased significantly.