The Variation Characteristics of Extreme Temperature in Karamayfrom 1961 to 2012

To explore the characteristics of climate change in Karamay and provide a theoretical basis for the local agricultural production,living condition and economic development,the research was carried out by using the method of percentiles threshold,the methods of linear trend analysis,Mann-Kendall test and wavelet analysis to analyze the variations of annual and seasonal extreme climate of Karamay in the light of the documented climate records from 1961 to 2012.Results:1)The frequency of maximum and minimum temperature events all had a decreasing trend and mutated in 1971 and 1981 respectively,and the periodicity were-1.5d/10a and-2.5d/10a,while the annual average maximum temperature exhibited a moderate growth tendency,the annual average minimum temperature,an increasing one,each at a growth rate of 0.007℃/10aand 0.288℃/10a;2)Among the seasonal average maximum temperature,winter had the biggest growth,increasing by 0.203℃/10a,followed by autumn,0.103℃/10a;summer had the biggest reduction,decreasing by-0.2℃/10a;followed by spring,-0.088℃/10a.As for the seasonal average minimum temperature,winter showed the most distinct growth,at a rate of 0.531℃/10a;followed by autumn,at 0.424℃/10a;summer,at 0.083℃/10a;finally,spring,at 0.056℃/10a.3)The amount of annual maximum and minimum temperature erupted in 1984 and 1976 respectively and the amount of annual minimum temperature experienced a distinct reduction since 1995.The annual average maximum temperature had a dramatic change in 1984,while the annual average minimum temperature,in1976,which showed an increasing tendency since 1990.Average maximum temperature in summer mutated in 2002,while the average minimum temperature in winter dramatically changed in 1976,and increased ever since.4)The periodicities of the amount of annual maximum and minimum temperature were 3a and 8a respectively.Annual average maximum and minimum temperature and average maximum temperature in summer showed no distinct change,whereas the periodicity of average minimum temperature in winter was 4a.