中文摘要：

位于青藏高原西南部的谢通门地区,是典型的高原半干旱地区之一,研究其降水变化特征具有重要意义.利用谢通门地区的大果圆柏（Sabina tibetica Kom.）树轮宽度资料,分析了树轮宽度对气候要素的响应特征.研究发现,制约树木径向生长的主要因子是年总降水.为兼顾分析气候序列在高低频域的变化特征,利用标准化年表通过方差匹配方法和采用差值年表通过线性回归方程转换,分别重建了谢通门公元1360～ 2013年间（644年）的年（上一年7月至当年6月）降水变化.基于标准化年表的重建结果表明,谢通门降水序列存在明显的年代际气候变化韵律,相对于平均值偏湿的持续时段发生在公元1360 ～ 1368年、1505 ～ 1599年、1631～ 1640年、1654～1797年、1825～1836年、1890～1901年和1975年之后;偏干的持续时段发生在公元1369～1504年、1600～1630年、1641～1653年、1798～1824年、1837～1889年和1902～ 1974年.与林周地区降水序列、高原南部区域降水序列和亚洲季风区PDSI网格重建中提取的邻近4个格点数据的平均序列对比发现,过去共同的640年内（公元1360～2000年）青藏高原南部地区经历了相同的干湿变化过程,在年代际尺度上变化一致,可能受到相同的气候驱动因子控制.空间相关性分析也表明,谢通门地区年降水变化具有一定的空间代表性,可以反映青藏高原西南部地区的降水变化.多窗谱分析（MTM）检测出该重建序列在过去644年中存在128a、3.5a、2.9a、2.5a和2.1a的显著周期.

英文摘要：

Situated on the southwestern Tibetan Plateau （TP）, the Xietongmen region is of typical semi-arid climate. Our tree-ring sites XMQ （29.80°N, 87.43°E; 4576-4781m a.s.1.） and XLB （30.10°N, 87.53°E; 4460m a.s.1.） are located in the Xietongmen County within the Nianchuhe Watershed, the Yarlung Tsangpo River. In total, 222 cores/112 trees of Tibetan junipers were collected. Tree growth/climate relationship was analyzed by calculating correlation and response coefficients between standard ring-width index of Xietongmen junipers and instrumental records during the 1957 -2013 common period. Results indicated the Xietongmen tree rings could be annual （prior July to current June） precipitation indicators for the study region. In order to discuss the climate variabilities in annual and decadal scales, annual （prior July to current June） precipitation during 1360-2013 A.D. （644 years） was reconstructed based on scaling and linear regression models according to the STD and RES chronologies, respectively. Decadal and multi-decadal variations were displayed by the regressed precipitation, relatively wet periods above the average precipitation occurred in 1360 - 1368A.D., 1505- 1599A.D., 1631 1640A.D., 1654 - 1797A.D., 1825- 1836A.D., 1890- 1901A.D. and after 1975A.D., whereas relatively dry periods below the average occurred in 1369- 1504A.D., 1600 - 1630A.D., 1641 - 1653A.D., 1798 - 1824A.D., 1837- 1889A.D. and 1902- 1974A.D. Compared with the Linzhou and regional precipitation series on the southern TP as well as four closest gridded-averaged PDSI series derived from the Monsoonal Asia Drought Atlas （MADA） datasets, consistent wet/dry variations were identified in decadal scales. Meanwhile, the Xietongmen precipitation reconstruction showed significant correlation with the Linzhou precipitation in annual scale （R = 0.34, p〈0.01 ） , indicating similar variability of local climatic variations. Spatial analysis showed the reconstructed precipitation could play spatial representation on the so