Indian Summer Monsoon variations and competing influences between hemispheres since ~35 ka recorded in Tengchongqinghai Lake, southwest China

Peng, J., Yang, X., Toney, J. L. , Ruan, J., Li, G., Zhou, Q., Gao, H., Xie, Y., Chen, Q. and Zhang, T. (2019) Indian Summer Monsoon variations and competing influences between hemispheres since ~35 ka recorded in Tengchongqinghai Lake, southwest China. Palaeogeography, Palaeoclimatology, Palaeoecology, 516, pp. 113-125. (doi: 10.1016/j.palaeo.2018.11.040)

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The southwestern Yunnan Province of China, which is located at the southeastern margin of the Tibetan Plateau and close to Bay of Bengal, is significantly influenced by the Indian Summer Monsoon (ISM). In this study, we reconstruct proxies for the ISM from 35 to 1 ka through detailed analysis of grain-size distribution, geochemical composition and environmental magnetism from a 7.96 m sediment core from Tengchongqinghai Lake, Yunnan Province, China. Globally recognized, abrupt climatic events, including Heinrich Events 0–3 (H0−H3) and the Bølling-Allerød (B/A) warm period are identified in most of our proxies, and the long-term trend is consistent with other published records such as stalagmite oxygen isotopes (δ18O) from Sangxing Cave. Northern Hemisphere (NH) temperature, which is influenced by NH solar insolation, is commonly suggested to play a dominant role in controlling the ISM. A comparison of our record with the δ18O variations of ice cores from Greenland and Antarctica, a sea surface temperature (SST) record from the Bay of Bengal, and summer solar insolation at 25°N latitude demonstrates that the general pattern of ISM change does follow variations in summer insolation; however, the ISM lags summer insolation by thousands of years. While the ISM fluctuations are highly correlated with NH temperature on shorter timescales (centennial-millennial), the gradually weakened ISM from 22.5 ka until the Last Glacial Maximum (LGM) indicates a close relationship with the rise of Southern Hemisphere (SH) temperature and the relatively cold background of the SH. Our record expands on the findings of ISM records from Heqing paleolake basin in southwestern China and the Arabian Sea sediments, suggesting that the NH and SH have a competitive influence on ISM by controlling the cross-equatorial pressure gradient. This relationship means that when NH temperatures are relatively high, it has a stronger influence on the ISM than SH influences. In contrast, when the SH temperature is relatively low, it has a dominant influence on ISM. In addition, we speculate that the change of SH temperature not only influences the cross-equatorial pressure gradient directly, but also likely modulates the circulation system of ocean energy by influencing the Atlantic Meridional Overturning Circulation (AMOC).

Item Type:Articles
Additional Information:This project was supported by NSFC (Natural Science Foundation of China; grant no. 41030366 and 41672162) and Guangdong Province Introduced Innovative R& D Team of Geological Processes and Natural Disasters around the South China Sea (grant no. 2106ZT06N331).
Glasgow Author(s) Enlighten ID:Toney, Professor Jaime
Authors: Peng, J., Yang, X., Toney, J. L., Ruan, J., Li, G., Zhou, Q., Gao, H., Xie, Y., Chen, Q., and Zhang, T.
College/School:College of Science and Engineering > School of Geographical and Earth Sciences
Journal Name:Palaeogeography, Palaeoclimatology, Palaeoecology
ISSN (Online):0031-0182
Published Online:04 December 2018
Copyright Holders:Copyright © 2018 Elsevier B.V.
First Published:First published in Palaeogeography, Palaeoclimatology, Palaeoecology 516:113-125
Publisher Policy:Reproduced in accordance with the copyright policy of the publisher

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