1. Different responses of precipitation patterns to the East Asian summer monsoon weakening: The 7.2 and 8.2 ka events.
- Author
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Pan, Liangkang, Zhao, Jingyao, Yang, Yan, Wang, Kexin, Pérez-Mejías, Carlos, Cui, Jiahui, Dong, Xiyu, Zhang, Rui, and Cheng, Hai
- Subjects
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MONSOONS , *PALEOHYDROLOGY , *CONDITIONED response , *SUMMER , *HOLOCENE Epoch , *DROUGHTS - Abstract
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. • In the 7.2 ka event, we observed more intense dryness in southwest China compared to the 8.2 ka event, despite the 7.2 event having a relatively stronger monsoon. • The precipitation patterns differed between the 7.2 ka event, 8.2 ka event, as well as the Early and Middle Holocene. During the 7.2 ka event, hydrological conditions exhibited a "north flood and south drought" pattern, while the 8.2 ka event was characterized by "spatially consistent drought." • The varying precipitation patterns under similar East Asian Summer Monsoon (EASM) intensities enhance our understanding of speleothem δ18O. This suggests that speleothem δ18O primarily reflects the dynamics of the EASM system rather than the thermodynamics. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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