Journal cover Journal topic
Climate of the Past An interactive open-access journal of the European Geosciences Union
https://doi.org/10.5194/cp-2017-110
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 4.0 License.
Research article
12 Oct 2017
Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Climate of the Past (CP).
Intensified Atlantic vs. weakened Pacific meridional overturning circulations in response to Tibetan Plateau uplift
Baohuang Su1,4, Dabang Jiang1,2,3, Ran Zhang1, Pierre Sepulchre5, and Gilles Ramstein5 1Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
2Joint Laboratory for Climate and Environmental Change at Chengdu University of Information Technology, Chengdu 610225, China
3CAS Center for Excellence in Tibetan Plateau Earth Sciences, Beijing 100101, China
4University of Chinese Academy of Sciences, Beijing 100049, China
5Laboratoire des Sciences du Climatet de l'Environnement/IPSL, CEA-CNRS-UVSQ, UMR8212, Orme des Merisiers, CE Saclay, 91191 Gif-sur-Yvette CEDEX, France
Abstract. The role of the Tibetan Plateau (TP) in maintaining large-scale overturning circulation in the Atlantic and Pacific is investigated using a coupled atmosphere–ocean model. For the present day with a realistic topography, model simulation shows a strong Atlantic meridional overturning circulation (AMOC) but a near absence of a Pacific meridional overturning circulation (PMOC), which is in good agreement with present observations. In contrast, the simulation without the TP depicts a collapsed AMOC and a strong PMOC that dominates deep water formation. The switch in deep water formation between the two basins results from changes in the large-scale atmospheric circulation and atmosphere–ocean feedback in the Atlantic and Pacific. The intensified westerly winds and increased freshwater flux over the North Atlantic cause an initial slowdown of the AMOC, but the weakened East Asian monsoon circulation and associated decreased freshwater flux over the North Pacific enhance initial intensification of the PMOC. The further decreased heat flux and the associated increase in sea-ice fraction promote the final AMOC collapse over the Atlantic, while the further increased heat flux leads to the final PMOC establishment over the Pacific. Although the simulations were done in a cold world, it still importantly implicates that the uplift of the TP alone could have been a potential driver for the reorganization of PMOC–AMOC between the Late Eocene and Early Oligocene.

Citation: Su, B., Jiang, D., Zhang, R., Sepulchre, P., and Ramstein, G.: Intensified Atlantic vs. weakened Pacific meridional overturning circulations in response to Tibetan Plateau uplift, Clim. Past Discuss., https://doi.org/10.5194/cp-2017-110, in review, 2017.
Baohuang Su et al.
Baohuang Su et al.
Baohuang Su et al.

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Short summary
The present numerical experiments undertaken by a coupled atmosphere–ocean model indicate that the uplift of the Tibetan Plateau alone could have been a potential driver for the reorganization of Pacific and Atlantic meridional overturning circulations between the Late Eocene and Early Oligocene. In other words, the Tibetan Plateau could play an important role in maintaining the current large-scale overturning circulation in the Atlantic and Pacific.
The present numerical experiments undertaken by a coupled atmosphere–ocean model indicate that...
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