中国天山区域云量的变化及其与降水的关系

The Change of Cloud Coverage in Tianshan Mountain in China and Its Relation with Precipitation

基于1961—2008年天山区域24站云量的逐日资料,使用相关和M原K检验等统计方法,分析中国天山区域云量的时空变化特征及其与降水的关系。结果表明:(1)春季、秋季和冬季,伊犁河谷以北总云量最多,夏季则在中天山和东天山的部分区域最多,低云量在夏季占总云量的比重最大;(2)区域平均总云量在春季和秋季呈减少趋势;低云量在各季节均呈增加趋势,尤其在冬季和夏季;(3)总云量的年代际变化不明显,而低云量自20世纪90年代至今,都处在高值期。(4)低云量在春季、夏季和秋季,均在20世纪90年代,而冬季在2000年左右发生了由少到多的气候突变;总云量未发生明显的气候突变。(5)总云量和低云量均和同期降水有较好的相关性。春季低云量和夏季降水,相关系数可达0.52。

Based on daily cloud coverage data at 24 stations in Tianshan Mountain area from 1961 to 2008, the spatial and temporal variation features of cloud coverage in Tianshan Mountain area were analyzed by the statistical methods, such as correlation and Mann-Kendall Test. The results showed：（1）the total cloud coverage in Yili valley and to its north was the most, but the low cloud coverage was the most in some areas of middle and eastern Tianshan mountains and the ratio between low cloud coverage and total cloud coverage was the most in summer;（2）the regional average total cloud coverage presented decreasing trend in spring and autumn, and the low cloud coverage for four seasons all presented increasing trends, especially in winter and summer;（3）the decadal variation of the total cloud coverage was not obvious, and it had been in high value period since 1990;（4）the climate jump of the low cloud coverage had occurred in spring, summer and autumn in 1990s, and in winter around 2000;（5）both of total cloud coverage and low cloud coverage had a good correlation with precipitation, especially the low cloud coverage in spring with summer precipitation and the correlation coefficient was 0.54.