嫩江流域降水特征时空分布分析

The spatiotemporal distribution of precipitationcharacteristics in Nenjiang River Basin

基于嫩江流域17个气象站点1959—2010年逐日降水数据,选取降水量、降水日数和降水强度作为代表性指标,采用Mann-Kendall趋势检验法和线性回归法系统研究了嫩江流域降水的时空变化特征。结果显示:近51年来,①嫩江流域平均年降水量、夏季和秋季降水量分别以6mm/(10a)、4mm/(10a)和5 mm/(10a)的速率呈下降趋势,而春、冬两季降水量分别以2mm/(10a)和1mm/(10a)的速率增加;空间上,年降水量和季节降水量在流域上游多于下游。②嫩江流域平均年、夏季和秋季降水日数分别以1.5d/(10a)、1.1d/(10a)和1.2d/(10a)的速率下降,且上游下降较明显;春、冬两季降水日数则以0.1d/(10a)、0.7d/(10a)的速率呈增加趋势,且中游增加趋势明显;流域降水日数在年和季节尺度上均表现出上游多于下游的空间特征。③嫩江流域平均年降水强度、夏季和秋季降水强度分别以-0.018mm/(d·10a),-0.007mm/(d·10a)和-0.105mm/(d·10a)下降,而春、冬两季降水强度分别以0.051mm/(d·10a)和0.047mm/(d·10a)上升;空间上,年和春、夏、冬3个季节降水强度表现为流域上游弱于下游,而秋季降水强度在嫩江中游干流附近较大,其他地区降水强度较小。结果表明,在全球气候变化下,嫩江流域年和季节的降水特征在1959—2010年间均有不同程度改变,并呈现出明显的空间分布特征。

Based on the daily precipitation data of 17 meteorological sites in the Nenjiang River Basin from 1959 to 2010,precipitation amount,precipitation days and precipitation intensity were selected as representative indicators,and the spatial and temporal change characteristics of precipitation in Nenjiang Basin were studied by Mann-Kendall trend test and linear regression method.The results show that,for nearly 51 years:①The average annual precipitation in the Nenjiang Basin,the precipitation in summer and autumn decreased at the rate of 6mm/(10a),4mm/(10a)and 5 mm/(10a),respectively,while the precipitation in spring and winter increased at a rate of 2mm/(10a)and 1mm/(10a);spatially,annual and seasonal precipitation in the upstream is more than downstream.②The average annual,summer and autumn precipitation days in the Nenjiang Basin decreased at a rate of 1.5d/(10a),1.1d/(10a)and 1.2d/(10a)respectively,and the decrease in the upstream was more obvious;the number of days of precipitation in the basin showed the spatial characteristics that is more in upstream than downstream on the year and seasonal scale.③The average annual precipitation intensity,summer and autumn precipitation intensity in the Nenjiang Basin decreased by-0.018 mm/(d.10a),-0.007mm/(d.10a)and-0.105mm/(d.10a),while the inereasing rate precipitation intensity in the spring and winter seasons was 0.051mm/d.10a and 0.047mm/da.Precipitation intensity of spring,summer and winter is shown to be weaker in the upper reaches of the basin than downstream,while the precipitation intensity in autumn is larger near the main stream in the middle of the Nenjiang River.The results show that under global climate change,the annual and seasonal precipitation characteristics in the Nenjiang River Basin during 1959—2010 have changed in different degrees,and exhibit obvious spatial distribution characteristics.