Temporal Trends Features And Spatial Distributions Of Extreme Climate Events In China

Extreme climate events are hot issues of academic research.Since the destructive effect caused by extreme climate events,it is of great theoretical and realistic significance to explore the spatial characteristics and distribution of extreme weather events.The data used in this paper came from The National Meteorological Bureau,including 756 meteorological stations.So we can use them to explore the spatial characteristics and distribution of extreme weather events on a national scale.In terms of innovation,this paper attempts to do a lot.Firstly,the Poisson Point theory and GEV distribution are applied,but the location parameter has been changed linearly.I use these theories to explore the trend features of extreme climate events and spatial-temporal features of return levels.Secondly,to analyze the change features in consecutive days of extreme climate events,the Poisson Regression is employed in this paper.Thirdly,the inter-decadal variations,the mutation point and the periodicity of extreme climate events are also investigated.The main researches are as follows:1.From the perspective of administrative regions,the frequency and intensity of extreme high temperature increased rapidly since 1990 s.Except Yunnan province,the other regions all have the type of(+,-)in consecutive days of extreme high temperature.Nationwide,the mutation point is 2005,thereafter,the frequency of extreme high temperature increased significantly.There exist the period of 2-3 years from 1951 to 2011,the period of 6-7 years from 1992-2009,and the period of 11-12 years from 1952-1958.From the view of stations,there are 412 stations show significant trends in extreme high temperature.There are 388 stations which have a rising trend.According to the spatial distribution of return level,the top six administration regions are Beijing,Anhui,Henan,Chongqing,Hebei and Xinjiang.The last two are Qinghai and Xizang.2.From the perspective of administrative regions,the frequency and intensity of extreme low temperature decreased rapidly since 1980 s.There are 20 administration regions,which have significant trend in consecutive days of extreme low temperature.Chongqing,Fujian,Guangdong,Guangxi,Guizhou,Hainan,Heilongjiang,Hubei,Qinghai,Shanxi,Xizang and Zhejiang have the type of(-,-);Gansu,Hebei,Henan,Jilin,Ningxia,Shaanxi,Tianjin and Xinjiang have the type of(+,-);Anhui,Beijing,Hunan,Jiangsu,Jiangxi,Liaoning,Neimenggu,Shanghai and Shandong have significant trends of decreasing.Nationwide,the mutation point is 1985,thereafter,the frequency of extreme low temperature decreased rapidly.There exist the period of 2-3 years from 1951-2011,and the period of 8-9 years from 1954-1974.From the view of stations,there are 172 stations show significant trends in extreme low temperature,and there are 168 stations which have decreasing trends,but their rate of decline are very small less than 1? over one hundred years.According to the spatial distribution of return level,there are three distribution zones.Heilongjiang,Neimenggu,and Jilin located in the Northeast,and Xinjiang,Xizang and Qinghai are located in the Northwest.The return level of these six provinces are less than-40?.The provinces whose return level are between-40? and-20? are located in the East.Yunnan,Guangdong,Guangxi and Hainan are southern provinces,whose return level are higher than-10?.3.From the perspective of administrative regions,during the 1950 s and 1960 s,provinces who has positive anomaly of frequency and intensity in extreme heavy precipitation are located in the eastern part.During 1970 s,the number of provinces who has positive anomaly is small,and these provinces are mainly located in the central part.After 1980 s,the frequency and intensity of extreme heavy precipitation in western provinces are increasing.The trends in consecutive days of extreme heavy precipitation are not distinct.Only three provinces,Fujian,Qinghai,and Yunnan have significant regression results of Poisson quadratic regression model.Hebei,Liaoning,Sichuan and Xinjiang have significant regression result of linear Poisson regression.For the whole country,the mutation point is 1957,thereafter,the intensity of extreme heavy precipitation decreased significantly.There is the period of 8-9 years from 1952 to 1966,from 1980 to 1986;the period of 2-3 years from 1974 to 1978,from 1990 to 1996,and the period of 13-14 years from 2000 to 2008.From the view of stations,there are 150 stations show significant trends in extreme heavy precipitation.These stations are mainly located in the south-central part.The spatial distribution of return level shows that these stations which have temporal trends also have higher return levels.4.Since 1980 s,the frequency of extreme drought events increased rapidly.The frequency of extreme drought events increased at a rate of 7.733 annually.The mutation point is 1980,thereafter the frequency increased rather more rapidly.The period of extreme drought events are 2-3 years during the period from 1952 to 1993.From 1956 to 1984,the period is 25 years,and from 1993 to 2008,the period is 10-11 years.From the point of view of each season,the frequency of extreme drought events has a significant rising trend at all seasons.Winter has the fastest growing speed of 4.657 annually.In autumn the grown rate is 2.996 annually.In spring and summer,the rate is much smaller,0.987 and 0.197 respectively.