利用1971-2010年雅鲁藏布江中游河谷地区拉萨、日喀则、泽当和江孜4个站逐日平均气温和降水量资料, 分析了该地区气候生长期变化特征。结果表明: (1)雅鲁藏布江中游地区各界限温度气候生长期以5～8 d·(10a)^-1的速率增加, 其中≥0℃和≥10℃界限温度的气候生长期都增加了30天左右, ≥5℃气候生长期增加了20天左右; 以稳定通过10℃界限温度来判断, 该地区冬半年时间在缩短, 夏半年时间在延长。(2)该地区稳定通过各界限温度的初日提前、终日推后, 持续天数和活动积温增加趋势显著; ≥10℃界限温度的降水量和降水日数增加趋势显著, 分别以19 mm·(10a)^-1和1.5 d·(10a)^-1的速率增加, 且在20世纪80年代末发生突变, 表明该地区稳定通过10℃界限温度的水热条件显著地向暖湿变化。(3)各界限温度的终日年际变化相对较稳定, 其他要素年际变化均处于不稳定状态; 年代际变化上, ≥10℃界限温度的初日、终日、持续天数以及各界限温度的活动积温保持台阶式变化, 其他要素呈波动变化, 最小值出现在20世纪80年代。(4)≥10℃界限温度的终日、持续天数和活动积温的变化趋势在20世纪90年代后期出现突变现象, 表明≥10℃界限温度的终日显著推后趋势对夏半年的延长贡献最大。

By using daily mean temperature and daily precipitation of Lasa, Rikaze, Zedang and Jiangzi in the middle course of Yarlung Zangbo River valley in 1971-2010, the variation of its climatic growing season was analyzed. The result shows: (1) The climatic growing season lengthened by 5~8 d·(10a)^-1 obviously, the climatic growing season of limit temperature ≥ 0℃ and ≥10℃ had increased by 30 d, limit temperature ≥ 5℃ had increased by 20 d; with limit temperature ≥ 10℃ being considered, the winter season shortened while the summer season lengthened. (2) The trend was significant of beginning dates advanced, ending dates deferred, lasting days and active accumulated temperature increased of three critical temperature; precipitation and ≥5 mm precipitation days of limit temperature ≥ 10℃ was increasing by 19 mm·(10a)^-1 and 1.5 d·(10a)^-1, and confirmed a mutation in the end of 1980s, indicating the precipitation and temperature conditions of limit temperature ≥ 10℃ was changing to warm-humid significantly. (3) The interannual variability of ending dates was relatively stable, and other elements was unstable; The decadal variability of the beginning and ending dates, lasting days and all accumulated temperature keep step changes, but other elements presented fluctuation changes, the minimum appeared in 1980s. (4) The variation trend of ending date, lasting days and accumulated temperature of limit temperature ≥ 10℃, which can be considered mutation in the latter of 1990s, indicating the largest contribution to the extension of the summer season came from the significant delay trend of limit temperature ≥ 10℃.