近54a来敦煌绿洲日照时数的变化特征分析

Analysis of change characteristics of sunshine hour in Dunhuang oasis in recent 54 years

利用敦煌绿洲1952～2005a逐月日照时数实测资料,采用一元线性回归、Mann-Kendall等方法,对敦煌绿洲日照时数的气候变化特征进行了分析。结果表明:54a来敦煌绿洲年日照时数呈增加趋势,其变化倾向率为2.7h/10a,增加的幅度不明显;在四季中,春、夏、秋季日照时数呈增加趋势并以春季增加最为显著,变化倾向率为5.5h/10a,对年日照时数的贡献率最大,冬季略呈减少趋势。通过Mann-Kendall检验得出,敦煌绿洲年日照时数在20世纪80年代的增加是突变现象,突变点发生在1987a;各季的日照时数在80年代后期和90年代初期是突变的多发期,这与年日照时数的突变时期基本一致。因此,各季日照时数发生突变是导致年日照时数发生突变的原因。

The climate change characteristics of annual,seasonal sunshine hour in Dunhuang oasis were analyzed based on the observed data of sunshine hour in Dunhuang Oasis in recent 55 years using the methods of simple linear regression and Mann-Kendall statistic etal.The mainly results were as follows：（1）The annual sunshine hours in Dunhuang oasis was increasing at the trend rate of 2.7h/10a and the trend was not evident.（2）In four seasons,the sunshine hours of spring,summer and autumn were increasing.This tendency appeared mainly in spring and the trend rate was 5.5h/10a.However,the tendency in winter was decreasing and the trend rate was-0.8h/10a.（3）The results of Mann-Kendall statistic revealed that the increase of the annual sunshine hour was an abrupt phenomenon and it happened around 1987 in Dunhuang oasis.In spring,the sunshine hour changed abruptly in 1959 and 1989.In summer,the sunshine hour changed abruptly in 1964 and 1994.In autumn,the sunshine hour changed abruptly in 1962 and 1987.In winter,the sunshine hour changed abruptly in 1954 and 1986.