Different responses of precipitation patterns to the East Asian summer monsoon weakening: The 7.2 and 8.2 ka events
Different responses of precipitation patterns to the East Asian summer monsoon weakening: The 7.2 and 8.2 ka events
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DOI：
10.1016/j.quascirev.2023.108329
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发表时间：
2023-11
影响因子：
4
通讯作者：
Liangkang Pan;Jingyao Zhao;Yan Yang;Kexin Wang;C. Pérez-Mejías;Jiahui Cui;Xiyu Dong;Rui Zhang-Rui
中科院分区：
文献类型：
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作者：
Liangkang Pan;Jingyao Zhao;Yan Yang;Kexin Wang;C. Pérez-Mejías;Jiahui Cui;Xiyu Dong;Rui Zhang-Rui
8.2 ka 突然冷却事件已被广泛研究，而 7.2 ka 事件及其比较却很少被提及。在这里，我们提出了来自张家洞（中国四川盆地北缘）的高分辨率（〜4年）和精确定年（±25年）的洞穴生物多代理记录，跨越早全新世到中期过渡期间的7.2和8.2 ka事件。洞穴化石δ18O主要反映东亚夏季风系统的动态特征，其δ13C和微量元素比值可作为当地水文条件的指标。我们的结果揭示了7.2ka事件期间中国西南地区的强烈干旱条件，尽管7.2ka事件的特点是与8.2ka事件相比相对较强的季风。此外，与东亚夏季风域不同古气候记录相比，7.2ka事件和全新世中期的水文条件呈现出“北涝南旱”的格局，而8.2ka事件则可概括为“空间一致干旱”。这些不同的水文条件是对东亚夏季风减弱的反应，这种现象在现代气候观测和经验模拟中也观察到，这支持了我们的理解，即洞穴δ18O变化主要是东亚夏季风系统的动力学表现，可能与其热力学外观不同。
The 8.2 ka abrupt cooling event has been extensively studied, whereas the 7.2 ka event and their comparations rarely mentioned. Here, we present a high resolution (∼4 years) and precisely dated (±25 years) speleothem multi-proxy record from Zhangjia Cave (northern margin of Sichuan basin, China) spanning the 7.2 and 8.2 ka events within the transition of early to middle Holocene. The speleothem δ18O mainly reflects the dynamic facets of the East Asian summer monsoon (EASM) system, while its δ13C and trace elements ratios serve as an indicator of local hydrological conditions. Our results reveal intense dry conditions in southwest China during the 7.2 ka event, despite the 7.2 event was characterized by a relatively stronger monsoon compared to the 8.2 ka event. Furthermore, the hydrological conditions during the 7.2 ka event and the middle Holocene appear to exhibit “north flood and south drought” pattern when compared to different paleoclimate records in EASM domains, while it can be summarized as “spatially consistent drought” in the 8.2 ka event. These different hydrological conditions are a response to the weakening of the EASM, a phenomenon also observed in modern climatic observations and empirical simulations, which underpins our understanding that the speleothem δ18O variations are mainly dynamical manifestations of the EASM system, likely different with its thermodynamical appearances.