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Assessing the Ability of Zonal δ 18 O Contrast in Benthic Foraminifera to Reconstruct Deglacial Evolution of Atlantic Meridional Overturning Circulation
Author(s) -
Gu Sifan,
Liu Zhengyu,
LynchStieglitz Jean,
Jahn Alexandra,
Zhang Jiaxu,
Lindsay Keith,
Wu Lixin
Publication year - 2019
Publication title -
paleoceanography and paleoclimatology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.927
H-Index - 127
eISSN - 2572-4525
pISSN - 2572-4517
DOI - 10.1029/2019pa003564
Subject(s) - deglaciation , geology , foraminifera , oceanography , antarctic bottom water , paleoceanography , north atlantic deep water , ocean current , thermohaline circulation , zonal and meridional , holocene , shutdown of thermohaline circulation , oceanic basin , climatology , structural basin , benthic zone , paleontology
δ 18 O in foraminifera (δ 18 O c ) is a useful proxy for density, and the strength of the Atlantic Meridional Overturning Circulation (AMOC) can be reconstructed by the zonal density contrast in the Atlantic. However, whether the deglacial zonal δ 18 O c contrast can represent the AMOC change is still unclear. δ 18 O c contrast across the Florida Straits has been hypothesized as a proxy for the AMOC evolution during the last deglaciation, but the strength of Florida Current could also be influenced by wind forcing. Here we examine the ability of the zonal δ 18 O c contrast to reconstruct AMOC in a deglacial model simulation. The model simulation suggests that the deglacial variation of the Florida Current strength is dominated by AMOC, with the wind effect on the variation of the Florida Current being negligible. Furthermore, the δ 18 O c contrast across the western boundary along the entire Atlantic and the basin‐wide δ 18 O c contrast in the North Atlantic in the upper ocean can also be used to reconstruct AMOC. However, using basin‐wide δ 18 O c contrast to reconstruct AMOC in the South Atlantic is not possible at all water depths. In the subtropical South Atlantic, the basin‐wide δ 18 O c contrast is decoupled from the density contrast between 400 to 600 m through the deglaciation because of the deglacial change of the Antarctic Intermediate Water. Therefore, δ 18 O c is a useful proxy to reconstruct past density and in turn past AMOC, but caution has to be used when using the basin‐wide δ 18 O c contrast to reconstruct the basin‐wide density contrast in the South Atlantic.