| Under the background of global warming,extreme climate events become more frequent,which has a serious impact on human life safety,economic development and natural ecosystem functions.This study of extreme climate events and the prediction under future scenarios is of great significance,which can provide important reference and basis for China’s climate risk assessment,flood control and disaster reduction.Based on the observed ground precipitation data recorded by 639 meteorological stations in China and the downscale datasets of CMIP6 global climate models,this study analyzes the spatiotemporal variation characteristics of extreme precipitation indices over China’s ten major basins during the reference period of 1961-2020,and the impact of urbanization on typical urban and rural stations in the Yangtze River Delta region.We also discuss the spatio-temporal variation characteristics of the floodheatwave compound extreme events and the independent extreme event of flood or heatwave events,investigate the difference between the compound events of flood-heatwave events in different periods of time,and compare the duration and average magnitude of heatwave in flood-heatwave events with the heawave events without flood before them.Finally,the changing characteristics of extreme precipitation indices,flood events,heatwave events and flood-heatwave events in China under four future scenarios are estimated,and the main conclusions are as follows:(1)During the reference period from 1961 to 2020,in addition to the consecutive dry days(CDD),the rest of extreme precipitation indices all show the spatial distribution characteristics of high in the southeast China and low in the northwest China.The number of stations with positive changing rates of precipitation intensity indices(RX1d,RX5 d,PRCPTOT,R95 P,R99P,SDII)and precipitation frequency indices(R10,R20,R25)exceed 50%,and the number of stations with positive changing rates of CDD and CWD are 31.5% and 37.6% respectively.Each basin presents different characteristics of precipitation indices and will face different climate disaster risks.Taking the Yangtze River Delta region as an example,we find that urbanization has positive effects on precipitation intensity indices and several precipitation frequency indices including R10,R20,R25,and has negative effects on CDD and CWD.(2)Except for a few stations,almost all stations in China experienced flood-heatwave events during 1961 to 2020 showing obvious spatial differences.The compound events occurred more frequently in Yangtze,Southeastern,Pearl and Northwest river basins,less frequently in Yellow,Hai,Songliao and Huai River basins.The total frequency and occurrence probability of flood and heatwave events showed a significant upward trend.Compared with the individual extreme events of flood and heatwave,the compound events of flood-heatwave had the fastest growth rate.Compared with heatwave events without flood before them,the longest duration and average magnitude of heatwave in flood-heatwave events were relatively short and weak respectively,which showed insignificant spatial differences among different basins.(3)Under the four future scenarios,except for CDD,the changing rates of the rest of extreme precipitation indices in China are all positive,and the changing rate of each indice increase with the increasing SSPs scenarios.The regional average difference of flood frequency among ten basins is not significant,while the spatial difference of heatwave frequency is relatively significant.Especially in the SSP585 scenario,China will exposed to more serious threat of high-temperature heatwaves.The changing rate of total frequency and occurrence probability of flood-heatwave compound events from 2021 to 2100 increases with the increasing of SSPs.Compared with the individual extreme events of flood and heatwave,the compound flood-heatwave events will increase more significantly in the future scenario,especially in Pearl,Songliao,Huai and Yellow River basins. |
PDF Full Text Request