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Amrhein, Daniel E.; Gebbie, Geoffrey; Marchal, Olivier; Wunsch, Carl. |
The ocean circulation modifies mixed layer (ML) tracer signals as they are communicated to the deep ocean by advection and mixing. We develop and apply a procedure for using tracer signals observed "upstream" (by planktonic foraminifera) and "downstream" (by benthic foraminifera) to constrain how tracer signals are modified by the intervening circulation and, by extension, to constrain properties of that circulation. A history of ML equilibrium calcite delta O-18 (delta O-18(c)) spanning the last deglaciation is inferred from a least-squares fit of eight benthic foraminiferal delta O-18(c) records to Green's function estimated for the modern ocean circulation. Disagreements between this history and the ML history implied by planktonic records would... |
Tipo: Text |
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Ano: 2015 |
URL: https://archimer.ifremer.fr/doc/00496/60726/65246.pdf |
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Gebbie, Geoffrey. |
The midpoint of the Last Termination occurred 4,000 years earlier in the deep Atlantic than the deep Pacific according to a pair of benthic foraminiferal delta O-18 records, seemingly implying an internal circulation shift because the lag is much longer than the deep radiocarbon age. Here a scenario where the lag is instead caused by regional surface boundary condition changes, delays due to oceanic transit timescales, and the interplay between temperature and seawater delta O-18 (delta O-18(w)) is quantified with a tracer transport model of the modern-day ocean circulation. Using an inverse method with individual Green functions for 2,806 surface sources, a time history of surface temperature and delta O-18(w) is reconstructed for the last 30,000 years... |
Tipo: Text |
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Ano: 2012 |
URL: https://archimer.ifremer.fr/doc/00265/37623/37003.pdf |
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