长江上游降水时空变化特征分析
Analysis of Spatiotemporal Variation Characteristics of Precipitation in the Upper Yangtze River

本文选取不同等级降水指标，基于长江上游地区687个站点1990~2020年的逐日降水量资料，采用线性倾向趋势法和Mann-Kendall检验法，对该流域总降水和不同等级降水的时空变化特征进行分析。结果表明：1) 近31年，长江上游地区总降水和除小雨外降水等级的降水量、日数及降水强度空间分布特征基本一致，呈现东南高，西北低的分布格局。各等级降水量、日数和强度变化趋势空间分布格局差异较大。2) 总降水和不同等级降水的时间变化特征主要体现为：长江上游地区总降水和小雨的年均降水量及日数呈显著的下降趋势，总降水强度显著上升，小雨降水强度下降但不显著。中雨年均降水量和日数呈下降趋势，但降水量未能通过95%的显著性检验，年均降水强度呈显著上升趋势。大雨和暴雨年均降水量、日数和降水强度上升，但变化不显著。3) 长江上游地区只有大雨和暴雨的降水量、降水日数和降水强度均发生突变。
In this paper, based on the daily precipitation data of 687 stations in the upper reaches of the Yangtze River from 1990 to 2020, the linear trend method and Mann-Kendall test were used to analyze the temporal and spatial variation characteristics of total precipitation and precipitation of different grades in this basin. The results show that: 1) In the past 31 years, the spatial distribution characteristics of precipitation, days and precipitation intensity of total precipitation and precipitation classes except light rain in the upper reaches of the Yangtze River are basically the same, showing a distribution pattern of high in southeast and low in northwest. The spatial distribution pattern of precipitation, number of days and intensity change trend of each grade had great differences. 2) The temporal variation characteristics of total precipitation and different grades of precipitation are as follows: the average annual precipitation and number of days of total precipitation and light rain in the upper reaches of the Yangtze River showed a significant downward trend, the total precipitation intensity increased significantly, and the light rain precipitation intensity decreased but not significantly. The average annual precipitation and days of moderate rain showed a downward trend, but the precipitation failed to pass the 95% significance test, and the average annual precipitation intensity showed a significant upward trend. The average annual precipitation, days and precipitation intensity of heavy rain and rainstorm increased, but the change was not significant. 3) In the upper reaches of the Yangtze River, only the precipitation of heavy rain and rainstorm, the number of precipitation days and precipitation intensity all had abrupt changes.