Research Of Group-occurring Extreme Temperature And Precipitation Events During 1960-2005

Based on a comprehensive review for extreme climate events,it is pointed out extreme weather and climate events have received increased attention in the last few years,due to the often large loss of human life and exponentially increasing costs associated with them. Therefore,the assessment and prediction of extreme climate events is an important field.Through the influence,group-occurring extreme climate events may create more potential for catastrophic impacts.There are number of ways group-occurring events can be understanded,this paper mostly means to spatial clusted events which belong to same events.We transform the meteorological factors to the weight of stations,finding that high weight stations are centralized instead of separated,which can be called group-occurring events.On the paper,group-occurring is the topic, how to delineate the group-occurring area is the masterstroke and kth-order nearest-distance arithmetic delineating clusterd events is the primary technique.On the basis of sush things,the group-occurring area is delineated,and annual,decadaI,regional analysis have been done.Many exciting results are achieved,which provide a new approach for the assessment of extreme climate events,the major conclusions of the study may be summarized as follow:Firstly,much theoretical research has been done.We introduced the algorithm of cluster extraction which is based on kth order nearest-distance,finding that kth order,the ratio of cluster and noise's densities and the number of data all have effect on the method.But the effect of the two formers are more important than the last one.This result is the base of the efficience test following.Furthermore,we introduced the concept of weight to extend the range of the simulated data,and gave the data different weights for delineating clusters,so that the range of the algorithm can be extended.Secondly,the possibility of algorithm's applying on the extreme events is analysed.12 kinds of temperature extremes and 6 kinds of extreme precipitation become the paper's objects.Based on the average ratio of cluster and noise's densities and efficient,we test all kinds of extreme climate event,finding that the algorithm is fit for group-occurring extreme climate events,especially for heavy events.Thirdly,temparture extremes defined by 99 percent,heavy rain and strong precipitation are the dominating objects.Chines region wiping off Sinkiang,Tibet and Leymus are the research scope.Based on the annual result of group-occurring stations about extreme climate events,we make attentions to the interannual varity of the number of group-occurring stations which can repress the group-occurring degree.We find that different extreme climate events have different turning point,which between middle of 1970s and midde of 1980s.Heavey rain has a notable decadal cycle,while strong precipitation has a obvious annual surge.It is provided that interannual variety is complex on group-occurring extreme climate events.Forthly,decadal group-occurring index if defined to access interdacadal variability.The result expressed that group-occurring decadal variability is consistent of the existing research.For example,strong precitpitation is unanimous of the existing dacacal variability.Fively,we investigate the annual and decadal climate characteristics of four major regions in eastern China,e.g.northerneast,north,south and central China.We are especially interested in the identity between the annual variation of climatic regions and the country as a whole in our annual cluster anlysis and find that the conformity of high temperatures of summer in northeast China is the worst.In the analysis of decadal characteristics,we draw a comparison between the climatic regions and three major metropolitan area of China(Jing-jin-tang Economic Circle,Yangtze River Delta and Perl River Delta).Results indicate that human-induced influences is somewhat reflected in the clustered extreme events in winter of Jing-jin-tang Economic Circle,however,no significant correlations can be drawn between three metropolitan area and the climatic regions it belongs to, e.g.the influence of anthropic factor on clustered extreme events is comparatively small.The lastly,based on large amount of literature consult and existing research work of extreme climate events,we find the obtained distribution of clustered extreme events is in good accordance with the observational data through making comparative analysis between the annual result of clustered extreme events after 1990 and historical records,thus certify the reliability of technical proposal in this paper and shows a new angle and direction of extreme climate event research. Furthermore,we investigate the correlation between clustered extreme events and its possible factor of influence,e.g.volcanic explosion,solar activity,index of monsoon and ENSO,and find the extreme climate events show a good response to the factors mentioned aboved.Volcanic explosion has relations to extreme high-temperature events.When the number of macula reduces,strong extreme climate events are likely to take place.Summer monsoon has effect to northeast extreme precipitation events while winter monsoon is contact with extreme temperature events on east of south China.ENSO events are possibly to happen in the years that strong extreme climate events take place.