Spatiotemporal Characteristics And Influencing Factors Of Extreme Precipitation During Typhoon Season In Coastal Areas Of Southeast China

Extreme precipitation and its secondary disasters pose serious risks to social economy and personal safety.Their impacts are even greater under changing climates.Understanding the relationship between extreme precipitation and climate and clarifying the regional differentiation of extreme precipitation play important roles in regional disaster risk warning,which improves disaster resistance capacity and reduces losses.Based on the summary of previous studies,this thesis focuses on typhoon(TCEP)and non-typhoon(n TCEP)related extreme precipitation from 94 meteorological observation stations in coastal areas of southeast China(including Jiangsu,Anhui,Shanghai,Zhejiang,Jiangxi,Fujian,and Guangdong Province)during July to September from 1964 to 2013.Difference in distribution and trends of both TCEP and n TCEP are analyzed.Based on climate indices and climate grid data(such as sea surface temperature(SST)and sea level pressure(SLP)),climate variables related to TCEP and nTCEP are analyzes and selected.Local models are established to quantify the impact of climate variables on extreme precipitation and to predict the distribution of extreme precipitation.Given the spatial information such as latitudes and longitudes of stations,regional models are established to quantify the relationship between extreme precipitation and spatial information.The conclusions of the thesis are as follows:(1)The data characteristics of TCEP and n TCEP are quite different.In terms of distributions,the longer the return period of extreme precipitation is,the more stations are where the extreme precipitation is typhoon related.When the return period is about10-year,the number of stations affected by typhoon reaches the most.In terms of regional characteristics,for both TCEP and n TCEP,there are upward trends of extreme precipitation in total areas,TCEP shows obvious spatial difference between north and south.(2)El Ni(?)o-Southern Oscillation(ENSO),Pacific Decadal Oscillation(PDO),North Pacific SST anomaly and North Indian Ocean SLP anomaly are main climate variables that influence the extreme precipitation in the typhoon season.The influence time of ENSO and PDO on extreme precipitation is relatively short,and their signals related to extreme precipitation in typhoon season can be observed in spring and summer.While the influence time of North Pacific SST anomaly and North Indian Ocean SLP anomaly is longer.Their correlation signals to extreme precipitation are detected as early as autumn and winter of the last year,which last for 8-10 months.(3)Distance to coastline(DTC)is important spatial information that leads to the spatial variation of extreme precipitation in the southeastern coastal areas of China.The closer the station to the coastline is,the greater the intensity of extreme precipitation is.In the case of the same distance to the coastline,for TCEP,the impact of DTC on the extreme precipitation at stations in Guangdong,Fujian and Zhejiang is 4-5 times that in the other regions.For TCEP,the influence of DTC on the intensity of extreme precipitation gradually decreases in stations from Guangdong to Jiangsu.