树轮记录的西北季风边缘区干旱变化

祁连山东部位于亚洲季风西北边缘区,对气候变化十分敏感。由于该区位于半干旱区,降水的变化直接影响人类社会经济的发展,所以研究该区干旱变化情况及其机制非常重要。利用采自祁连山东部西北季风边缘、地处半干旱区的吐鲁沟地区的油松树轮样芯,建立了树轮宽度年表,时间跨度为1866-2003AD。树轮宽度年表与气象因子相关分析结果显示树木生长主要响应生长季内的降水和干旱变化。该年表与附近区域利用树轮宽度重建的帕尔默干旱指数(PDSI)进行对比,结果显示严重的干旱时间发生在1920s-1930s、1966年、1974年、1982年和1990s和21世纪初。多窗谱分析研究表明,该区年表序列存在显著的2~4 a周期(P0.05),该周期与ENSO变率吻合,与在贺兰山、祁连山其他地区、兴隆山及贵清山研究结果一致,表明这些区域可能受共同气候因子的影响。

Tree-ring recorded of the drought variability in the northwest monsoon marginal,China

It is sensitive to climate change that the boundary of the northwest monsoon region as the northern boundary of the Asian summer monsoon.Knowledge of natural drought variability and the mechanism is essential for the development for human society and economy,especially in add and sub-arid regions.Here we present a new tree-ring chronology from Tulugou,in the eastern Qilian Mountains.The correlation analysis between the tree ring width and meteorological factor showed that tree growth response to the drought in the growing season.And we compared the chronology and the nearby drought reconstructions,and the results showed that persistently drought periods occurred in the 1920s-1930s,1966,1974,1982,1990s and early 21st century.Multitaper method spectral analysis indicates the existence of significant peaks at 2～4 years,suggesting a possible connection with the E1 Nino-Southern Oscillation.The results of the study are agreement with those of Helan Mountains,Qilian Mountains,Xinglong Mountains and Guiqing Mountains,which indicate that these areas may be influenced by the same climatic factors.