Northwestward shift of the northern boundary of the East Asian summer monsoon during the mid-Holocene caused by orbital forcing and vegetation feedbacks

QUATERNARY SCIENCE REVIEWS

卷:268

Article

Chen, Jie^1,2,3  Zhang, Qiong^2,3  Huang, Wei¹  Lu, Zhengyao⁴  Zhang, Zhiping¹  Chen, Fahu^1,5,6 

[1] Lanzhou Univ, Coll Earth & Environm Sci, Key Lab Western Chinas Environm Syst, Minist Educ, Lanzhou 730000, Peoples R China

[2] Stockholm Univ, Dept Phys Geog, S-10691 Stockholm, Sweden

[3] Stockholm Univ, Bolin Ctr Climate Res, S-10691 Stockholm, Sweden

[4] Lund Univ, Dept Phys Geog & Ecosyst Sci, S-22100 Lund, Sweden

[5] Chinese Acad Sci, Inst Tibetan Plateau Res, Key Lab Alpine Ecol LAE, Beijing 100101, Peoples R China

[6] Chinese Acad Sci, CAS Ctr Excellence Tibetan Plateau Earth Sci, Beijing 100101, Peoples R China

关键词: East Asian summer monsoon northern boundary;    East Asian westerly jet;    Mid-Holocene;    Orbital forcing;    Vegetation feedbacks;   

DOI  :  10.1016/j.quascirev.2021.107136

来源: Elsevier

【 摘 要 】

The East Asian summer monsoon (EASM) northern boundary is a critical indicator of EASM variations. Movement of the boundary is modulated by both the EASM and the mid-latitude westerlies. Here, we use the Earth system model EC-Earth to quantify the contribution of orbital forcing and vegetation feedbacks in modulating the movement of EASM northern boundary. The results show that the simulated EASM northern boundary during the mid-Holocene shifts by a maximum of similar to 213 km northwestward due to orbital forcing. When the model was coupled with a dynamic vegetation module LPJ-GUESS, the northern boundary shifts further northwestward by a maximum of similar to 90 km, indicating the importance of vegetation feedbacks. During the mid-Holocene, temperature increased in the mid-latitude during the boreal summer due to insolation, leading to increased meridional air temperature differences (MTDs) over the region north of 45 degrees N and to decreased MTDs to the south. The changes in the temperature gradient weakened the East Asian Westly Jet (EAWJ) and displaced it northward, resulting in an earlier transition of the Meiyu stage and a more prolonged Midsummer stage. The northward movement of EAWJ, combined with the enhanced southerly moisture flow from South China, caused more precipitation in North China and eventually to a northwestward shift of the northern boundary of the EASM. The coupled dynamic vegetation module LPJ-GUESS simulated more grassland and less forest over Northeast Asia during the mid-Holocene. The increased surface albedo tended to lower the temperature in the region, and further enhanced the MTDs in mid-latitude East Asia, leading to the further northward movement of the EAWJ and a northwestward shift of the EASM northern boundary. Although the simulated vegetation distribution in several regions may be not accurate, it reflects the substantial contribution of climate-vegetation interaction on modulating the EASM. (C) 2021 The Authors. Published by Elsevier Ltd.

【 授权许可】

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