A quantitative reconstruction of Holocene annual precipitation in the marginal zone of the East Asian summer monsoon
2022
Wang, Yuchen | Han, Zhiyong | Zhou, Yuwen | Zheng, Run | Li, Xusheng | Wang, Yong | Yi, Shuangwen | Lu, Huayu
There is great controversy regarding variations in the East Asian summer monsoon (EASM) during the Holocene. Simulations and modern observations have revealed that a strengthened EASM results in more precipitation in the monsoon marginal zone. Therefore, quantitative reconstruction of precipitation in this region is the key to revealing monsoon variability. Here, two closed-basin lakes, namely, Angulinao Lake and Dali Lake, with similar weather conditions on the southeastern margin of the Mongolian Plateau are studied. The Angulinao paleolake level is established by optically stimulated luminescence (OSL) dating of 17 beach ridges. The annual precipitation (AP) is calculated for Angulinao and Dali Lakes using a hydrological and energy balance model. A composite precipitation curve is obtained, which shows that the AP increased with time during the early Holocene, reached its maximum 9.2 ka, was generally high in the middle Holocene with two events of decreasing AP 7.7 ka and 5.2 ka, and decreased abruptly beginning 4.4–4.2 ka, followed by a continuous reduction to the lowest level observed at present. These results suggest that the oxygen isotopes of speleothems are proxies for EASM (circulation) intensity, the simulated AP does not underestimate the Holocene peak precipitation, and the pollen-based AP in neighboring lakes underestimates the early Holocene precipitation and fails to capture the precipitation peak 9.2 ka.
اظهر المزيد [+] اقل [-]الكلمات المفتاحية الخاصة بالمكنز الزراعي (أجروفوك)
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