大渡河流域降水的时空变化特征分析
Analysis on Spatiotemporal Variation Characteristics of Precipitation in Dadu River Basin

为了对大渡河流域降水的时间、空间分布特征有更加深刻的了解，本文使用1979~2018年欧洲数值预报中心的ERA5再分析的格点数据，通过利用月、季、年尺度上均值、方差和降水变率对降水量进行空间特征分析，使用Mann-Kendall检验法、小波分析、滤波，对降水量进行时间特征分析，结果表明：(1) 大渡河流域上游在各个尺度上降水量都少且降水均匀集中。(2) 大渡河流域中游雅安地区(石棉到汉源一带)是降水高值区，月、季、年尺度上分别有700 mm、1800 mm、4500 mm。(3) 大渡河流域下游降水在各个尺度上降水量都高于上游。(4) 大渡河流域降水在2002年发生突变。此前，降水整体趋势增加；此后，降水整体趋势减少。(5) 大渡河流域降水存在47.6个月的主周期。(6) 对月降水距平数值进行47.6个月的低通滤波后，发现降水整体趋势是在减少，振动频率不稳定，振动周期不规律。
In order to have a deeper understanding of the temporal and spatial distribution characteristics of precipitation in Dadu River Basin, the grid point data (ERA5) from the European Centre for Medium-Range Weather Forecasts from 1979 to 2018 were used to analyze the spatial characteristics of precipitation by using the mean, variance and precipitation variability on the monthly, seasonal and annual scales, and the time characteristics of precipitation were analyzed by using the Mann-Kendall test, wavelet analysis and filtering in this paper. The results show that: (1) The precipitation in the upper reaches of Dadu River Basin is small and uniform on all scales. (2) The area from Shimian to Hanyuan in the middle reaches of Dadu River Basin is a high value area of precipitation, with monthly, seasonal and annual scales of 700 mm, 1800 mm and 4500 mm respectively. (3) The precipitation in the lower reaches of Dadu River Basin is slightly higher than that in the upper reaches at all scales. (4) The precipitation in Dadu River basin changed suddenly in 2002. Before that, the overall trend of precipitation increased; after that, the overall trend of precipitation decreased. (5) The main period of precipitation in Dadu River Basin is 47.6 months. (6) After 47.6 months of low-pass filtering, it is found that the overall trend of precipitation is decreasing, the vibration frequency is unstable and the vibration period is irregular.