基于CMIP6的黄河流域极端降水时空特征分析

Spatiotemporal characteristics of extreme precipitation in the Yellow River basin based on CMIP6

全球变暖背景下,极端降水灾害风险增加,严重影响了人们的生命安全,对区域经济发展造成了严重的威胁.黄河流域是重要的生态屏障和经济地带,推动黄河流域生态保护和高质量发展已成为中国国家战略.因此本文对黄河流域极端降水事件过去及未来的特征进行了研究,发现:1)1975−2014年,空间分布上各极端降水指数呈现西北低、东南高的格局.时间变化上,除年降水量、中雨时间、5日最大降水量呈微弱的下降趋势外,其余各指数均呈上升趋势但不显著,极端降水事件较少.2)2015−2100年,各极端降水指数呈现显著的上升趋势,各极端降水指数的多年均值在空间分布格局上与历史时期相似,排放升高,辐射力变大,极端降水指数呈现显著增加的区域面积不断扩大.在SSP1-2.6情景和SSP2-4.5情景下,黄河流域呈现显著增加的区域集中于西南部,而在SSP3-7.0和SSP5-8.5情景下,除西南地区外,东部大部分地区极端降水呈显著增加,除年降水量外,其余各极端降水指数随着排放升高呈现显著减小趋势的区域逐渐集中于甘肃、青海两省.3)黄河流域四季的年均降水量均呈上升趋势,不同季节均具有湿润化的发展趋势.除宁夏外,其他地区的日最大降水量和5日最大降水量2种指数在四季均呈现不同程度的上升趋势,各地区这2种指数的最大值集中在7月份,预估未来时期黄河流域的暴雨洪涝灾害主要发生在夏季.本研究可为黄河流域极端降水的防范提供有效依据,为黄河流域高质量发展提供科学参考.

Due to global warming,the risk of extreme precipitation disasters has increased.This has seriously affected people’s life safety and posed serious threat to regional economic development.The Yellow River basin is an important ecological barrier and economic zone.Promoting the ecological protection and high-quality development in the Yellow River basin has become China’s national strategy.Therefore,we studied the past and future characteristics of extreme precipitation events in the Yellow River basin.From 1975 to 2014,all extreme precipitation indices showed decreasing trends from southeast to northwest.On the temporal scale,almost all extreme precipitation indices(exceptions:total wet-day precipitation,number of heavy precipitation days and max 5-day precipitation amount)showed insignificant increasing trends.Extreme precipitation events are few and far between.Extreme precipitation index showed a significant upward trend from 2015 to 2100,spatial distribution pattern of multi-annual mean value of extreme precipitation index was similar to past historical period.With increased emission,greater radiation force,area of extreme precipitation index continued to increase significantly.Under SSP1-2.6 and SSP2-4.5 scenarios,area with significant increase concentrated in the southwest.Under SSP3-7.0 and SSP5-8.5 scenarios,extreme precipitation in most of the eastern region(exception:southwest region)showed a significant increase.In addition to annual precipitation,other extreme precipitation index showed a significant decreasing trend,concentrating in Gansu and Qinghai provinces.Annual average precipitation in the Yellow River basin in four seasons shows an increasing trend,and there is a trend of wet weathers in different seasons.Index of max1-day and max 5-day precipitation amounts in all regions other than Ningxia showed varied increasing trend in the four seasons.Peak max 1-day and max 5-day precipitation largely concentrated in July.Rainstorm and flood disasters in the future will also likely to occur in the summer in the Yellow River basin.