摘要
青藏高原的极端干旱事件会导致高原内部河流的水文异常,进而对流域内的农业生产和人类生活产生巨大影响.然而,干旱事件发生的时空规律及其与全球变化的关系尚不明确.气象器测资料相对较短是极端干旱事件研究中的一个重要限制因素.本文利用西藏昌都地区3个采样点（马秀、热玉和腊久）的大果圆柏（Sabina tibetica Kom.）树轮宽度数据,分析了自1560年以来该区域极端干旱事件发生的特征.分析结果表明,树轮宽度可指示5～8月标准化降水蒸散指数（Standardized Precipitation-Evapotranspiration Index,简称SPEI）,3个采样点树轮年表20世纪共同的极低生长年份（1972年、1984年和1995年）与藏东南地区20世纪的区域干旱事件一致（1954～2006年）;在过去447年间（1560～2006年）,3个采样点共同的极端干旱事件发生最频繁的时期为1650～ 1700年间,多达6次/50年,发生最少的时期有1600～1650年、1800～1850年和1950～ 2000年,每50年仅有1次;在20世纪,极端干旱事件的发生频率低于历史上的平均值.极端干旱发生最频繁的1650～1700年对应于太阳活动较弱的蒙德极小期（Maunder Minimum）.研究结果有助于进一步认识青藏高原极端干旱事件的发生规律及其与全球气候变化的关系.
Extreme drought events on the Qinghai-Tibetan Plateau （QTP） could not only result in hydrological anomalies to the plateau-originated rivers but also involve deep influences on all systems to human beings within the watersheds. However, the spatio-temporal patterns of occurrences of extreme drought events and their linkages to large scale climate circulations and global changes are rarely understood. Few researches are developed related to extreme drought events was due to short meteorological and hydrologic records. In this study, we collected tree-ring samples （Sabina tibetica Kom.） from three sites on the southeast QTP （Maxiu. 31.08°N, 94.58OE; Reyu： 31.16°N, 95.24°E; Lajiu： 30-58°N, 96.18°E）. To select climate sensitive trees, old trees with habitats characterized by shallow soil layers and more open canopy covers were preferred during the field sampling. Following the standard dendrochronological methods, we mounted, polished, cross-dated, and measured tree core samples. The successfully cross-dated tree ring width series were then subjected to ARSTAN software to be detrended using spline functions with 50% frequency response cutoff with half of the full length of the tree cores. Tree ring index was calculated as ratios of the raw measurements and the detrending functions for each core. To exclude autocorrelation effects, we derived residuals though fitting an autoregression model for each detrended tree ring index sequence. These residual series were at last averaged using bi-weight robust mean method to develop a chronology for each site （site chronology）, as well as for the latter pooled dataset （the regional chronology）. Climate data, including monthly mean temperature, monthly mean maximum temperature, monthly mean minimum temperature, monthly total precipitation, and monthly mean relative air humidity, was obtained from the Dingqing Meteorological Station （31.42°N, 95.6°E） Besides, Standardized Precipitation-Evapotranspiration Index （SPEI） with a 1
出处
《第四纪研究》
CAS
CSCD
北大核心
2015年第5期1093-1101,共9页
Quaternary Sciences
基金
国家自然科学基金项目（批准号：31330015,31170419和31300409）资助
致谢感谢中国科学院植物研究所树轮实验室的老师和同学在野外采样,室内树轮测量和交叉定年以及数据分析中的帮助.
关键词
青藏高原
树木年轮
SPEI
极端干旱事件
the southeast Qinghai-Tibetan Plateau, tree rings, SPEI, extreme drought events
