| Autor: |
Sifan Gu, Zhengyu Liu, Hong Chin Ng, Lynch-Stieglitz, Jean, McManus, Jerry F., Spall, Michael, Jahn, Alexandra, Chengfei He, Lingwei Li, Mi Yan, Lixin Wu |
| Předmět: |
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| Zdroj: |
Proceedings of the National Academy of Sciences of the United States of America; 11/5/2024, Vol. 121 Issue 45, p1-8, 27p |
| Abstrakt: |
Abundant proxy records suggest a profound reorganization of the Atlantic Meridional Overturning Circulation (AMOC) during the Last Glacial Maximum (LGM, ~21,000 y ago), with the North Atlantic Deep Water (NADW) shoaling significantly relative to the present-day (PD) and forming Glacial North Atlantic Intermediate Water (GNAIW). However, almost all previous observational and modeling studies have focused on the zonal mean two-dimensional AMOC feature, while recent progress in the understanding of modern AMOC reveals a more complicated three-dimensional structure, with NADW penetrating from the subpolar North Atlantic to lower latitude through different pathways. Here, combining 231Pa/230Th reconstructions and model simulations, we uncover a significant change in the three-dimensional structure of the glacial AMOC. Specifically, the mid-latitude eastern pathway (EP), located east of the Mid-Atlantic Ridge and transporting about half of the PD NADW from the subpolar gyre to the subtropical gyre, experienced substantial intensification during the LGM. A greater portion of the GNAIW was transported in the eastern basin during the LGM compared to NADW at the PD, resulting in opposite 231Pa/230Th changes between eastern and western basins during the LGM. Furthermore, in contrast to the wind-steering mechanism of EP at PD, the intensified LGM EP was caused primarily by the rim current forced by the basin-scale open-ocean convection over the subpolar North Atlantic. Our results underscore the importance of accounting for three-dimensional oceanographic changes to achieve more accurate reconstructions of past AMOC. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
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