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| Titel |
Fueling export production: nutrient return pathways from the deep ocean and their dependence on the Meridional Overturning Circulation |
| VerfasserIn |
J. B. Palter, J. L. Sarmiento, A. Gnanadesikan, J. Simeon, R. D. Slater |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 7, no. 11 ; Nr. 7, no. 11 (2010-11-10), S.3549-3568 |
| Datensatznummer |
250005057
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| Publikation (Nr.) |
 copernicus.org/bg-7-3549-2010.pdf |
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| Zusammenfassung |
| In the Southern Ocean, mixing and upwelling in the
presence of heat and freshwater surface fluxes transform subpycnocline water
to lighter densities as part of the upward branch of the Meridional
Overturning Circulation (MOC). One hypothesized impact of this
transformation is the restoration of nutrients to the global pycnocline,
without which biological productivity at low latitudes would be
significantly reduced. Here we use a novel set of modeling experiments to
explore the causes and consequences of the Southern Ocean nutrient return
pathway. Specifically, we quantify the contribution to global productivity
of nutrients that rise from the ocean interior in the Southern Ocean, the
northern high latitudes, and by mixing across the low latitude pycnocline.
In addition, we evaluate how the strength of the Southern Ocean winds and
the parameterizations of subgridscale processes change the dominant nutrient
return pathways in the ocean. Our results suggest that nutrients upwelled
from the deep ocean in the Antarctic Circumpolar Current and subducted in
Subantartic Mode Water support between 33 and 75% of global export
production between 30° S and 30° N. The high end of this range results
from an ocean model in which the MOC is driven primarily by wind-induced
Southern Ocean upwelling, a configuration favored due to its fidelity to
tracer data, while the low end results from an MOC driven by high diapycnal
diffusivity in the pycnocline. In all models, nutrients exported in the SAMW
layer are utilized and converted rapidly (in less than 40 years) to
remineralized nutrients, explaining previous modeling results that showed
little influence of the drawdown of SAMW surface nutrients on atmospheric
carbon concentrations. |
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