近42年西藏高原雅鲁藏布江中游夏季气候趋势和突变分析

根据1957－1998年雅鲁藏布江中游拉萨、日喀则、泽当、江孜4个站6－8月的平均气温、降水资料，通过线性趋势估计和多项式函数拟合等方法分析了雅鲁藏布江中游地区夏季气候长期趋势变化和周期变化，并利用滑动T检验等方法讨论了突变的问题。结果表明：在过去42a里，该流域夏季气温有明显的上升趋势，1980年突变增暖非常明显；而夏季降水呈下降趋势，60年代中后期至80年代末降水普遍偏少，90年代降水出现回升势头。气温、降水的主要周期集中在高频波段，显著周期为2．8－3．5a。

Analyses of Climatic Trend and Jump over Middle Reaches of Yarlung Zangbo River in Tibetan Plateau in Recent 42 Years

The climatic variation tendencies and interdecadal variations over middle reaches of Yarlung Zangbo River in Tibetan Plateau are analyzed by using the observed data of summer mean temperature/precipitation at 4 stations ( Lasha, Xigaze, Zedang and Jiangzi) from 1957 to 1998. The main results are as follows: There exists respectively significant ascent and descent trends for summer temperature and rainfall over this region in recent 42 years. An obvious climatic jump of summer temperature occurs in late 1970's through early 1980's. From the middle of 1960's to 1980's the summer rainfall was obviously below the normal in this area. However, there was an increasing trend of rainfall after 1990. Summer temperature and precipitation have the oscillation period of 2~3 years.