长江上游极端降水时空变化特征分析

Analysis of Temporal and Spatial Variation Characteristic of Extreme Precipitation in the Upper Yangtze River

摘要: 本文采用中国气象科学数据共享服务网提供的1990~2020年长江流域地区687个气象站点逐日的降水数据，利用线性回归分析、Mann-Kendall趋势检验、滑动T检验、小波分析等，对1990~2020年的年和夏季极端降水进行时空变化特征分析，结果表明：1) 近31年年和夏季极端降水指数分布特征相似，持续干期(CDD)整体均表现出西北向东南递减趋势，降水强度(SDII)、强降水量(R95p)、湿日降水量(PRCPTOT)分布较为一致，整体均表现出西北向东南递增的趋势。年和夏季极端降水指数分布特征均表明青海沱沱河西部地区干旱形势较为严峻。2) 极端降水指数年变化趋势结果表明，长江上游地区连续降水事件的持续时间有所缩短，意味着长江上游地区的降水过程以持续时间较短的降水模式为主，31a长江上游北部地区极端降水增加趋势比南部地区更显著，夏季变化趋势图则发现东部地区极端降水增加趋势最为明显。3) 时间变化上，近31年长江上游地区年和夏季极端降水指数的线性趋势均表明PRCPTOT呈下降趋势，CDD、SDII均呈上升趋势，R95p在年和夏季上表现有所不同，夏季R95p呈下降趋势，年R95p则相反，且所有指数均通过0.1的显著性水平。4) 长江上游地区极端降水指数年显著性周期为2~4年，夏季显著性周期为2~3年。SDII和R95p在年和夏季中均存在突变年，年极端降水指数SDII突变主要发生在2012年和2014年，R95p突变主要发生在2012，夏季SDII突变主要发生在1996年，R95p主要发生在2015年。

Abstract: To study the impact of extreme precipitation on the upper Yangtze River region, the day-by-day precipitation data from 687 meteorological stations in the Yangtze River basin area from 1990 to 2020 provided by the China Meteorological Science Data Sharing Service Network were used, and linear regression analysis, Mann-Kendall trend test, sliding t-test, and wavelet analysis were used to conduct the annual and summer extreme precipitation. The results show that 1) the distribution characteristics of annual and summer extreme precipitation indices are similar in the past 31 years, and the continuous dry period (CDD) shows an overall decreasing trend from northwest to southeast, and the distribution of precipitation intensity (SDII), intense precipitation (R95p), and wet daily precipitation (PRCPTOT) are more consistent, and the overall shows an increasing trend from northwest to southeast. Both the annual and summer extreme precipitation index distribution characteristics indicate a more severe drought situation in the western part of Qinghai Tuotuo River. 2) The results of the annual trend of extreme precipitation index show that the duration of continuous precipitation events in the upper reaches of the Yangtze River has been shortened, implying that the precipitation process in the upper reaches of the Yangtze River is dominated by precipitation patterns of shorter duration. 31a the increasing trend of extreme precipitation in the northern areas of the upper reaches of the Yangtze River is more significant than that in the southern areas, while the summer trend map finds the most obvious increasing trend of extreme precipitation in the eastern areas. 3) In terms of temporal changes, the linear trends of both annual and summer extreme precipitation indices in the upper Yangtze River region in the last 31 years show that PRCPTOT has a decreasing trend, CDD and SDII have an increasing trend, and R95p behaves differently on annual and summer, with summer R95p showing a decreasing trend and annual R95p the opposite, and all indices pass the significance level of 0.1. 4) The annual significance cycle of extreme precipitation indices in the upper Yangtze River is 2~4 years, and the summer significance cycle is 2~3 years. R95p occurred mainly in 2015.