本项目, 主要在我国亚洲夏季风与北半球中纬度反气旋西风急流和西伯利亚高压相互作用最敏感的黄土高原西部与青藏高原东部万象洞现代洞穴稳定同位素体系研究的基础上,对生长在倒数第二次冰期内结晶致密、铀含量高而碎屑钍含量很低的6根石笋进行绝对高精度Th-230定年(误差~600 a左右)和高分辨率(5a)氧碳同位素分析, 研究与MIS3背景轨道框架和边界条件不同的冰期内亚洲夏季风强度变化在季风边缘区波动的幅度与模式, 精细解剖千年/亚千年尺度上亚洲夏季风突发性极端减弱/加强事件的结构形式、准确年代、持续时间、频谱规律和转换特点, 与北半球高/中纬度冬季主导的陆海气候记录、夏季主导的热带海陆记录、南半球高/中纬度冬季主导的陆海气候记录对比, 研究北-南两极通过南北中纬度冬季反气旋与北南热带夏季风之间的联系, 进而探讨千年-亚千年尺度上亚洲夏季风强度的变化与全球气候变化的相应与驱动机理.

This project monitors the modern stable isotopic system in Wanxiang cave between western Loess plateau and eastern Qinghai-Tibetan Plateau, the most sensitive region interacted by Asian summer monsoon and anticyclical westerly jet and Siberian Highs in the mid-latitude Northern Hemisphere. The six crystal compacted stalagmites with higher Uranium content and lower debris Thorium content growing during Penultimate Glaciation are carried out by the absolute high accuracy of Th-230 dating (errors ~600 a) and high resolution of oxygen and carbon isotope analysis (5a). The fluctuating amplitude and pattern of the variation of Asian summer monsoon intensity in the monsoon fringe area in different glacial periods with different background orbital frames and boundary conditions were studied, differed from MIS3. We do the detailed anatomy for the structural style, precise age, duration, spectrum and transformation characteristics of sudden extremely weakening/strengthening events of Asian summer monsoon at the millennial/sub-millennial scales. Compared with the winter-dominated high/mid-latitude land and sea climatic records in the Northern Hemisphere, summer-dominated tropical sea-land records, and winter-dominated high/mid-latitude land and sea climate records in the southern hemisphere, we reveal the coupling relationship between the north and south poles through the mid-latitude winter anticyclone and the tropical summer monsoon in the north and south. In this project, the change of Asian summer monsoon intensity and the corresponding driving mechanism of global climate change are further discussed.