Variability in subtropical‐tropical cells drives oxygen levels in the tropical Pacific Ocean

Duteil, Olaf; Böning, Claus W.; Oschlies, Andreas

doi:10.1002/2014gl061774

Cited by 44 publications

(59 citation statements)

References 33 publications

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“…The potential impact of changes in the tropical trade winds has been investigated recently by Ridder and England [], who found a direct correlation between changes in the strength of the trade winds and the spatial extent of the OMZ. This agrees with Duteil et al [] who suggest that the strength of the wind‐driven subtropical‐tropical cells is closely correlated with thermocline oxygen levels in the EEP.…”

Section: Introductionsupporting

confidence: 93%

Simulated effects of southern hemispheric wind changes on the Pacific oxygen minimum zone

Getzlaff

Dietze

Oschlies

2016

Geophysical Research Letters

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A coupled ocean biogeochemistry‐circulation model is used to investigate the impact of observed past and anticipated future wind changes in the Southern Hemisphere on the oxygen minimum zone in the tropical Pacific. We consider the industrial period until the end of the 21st century and distinguish effects due to a strengthening of the westerlies from effects of a southward shift of the westerlies that is accompanied by a poleward expansion of the tropical trade winds. Our model results show that a strengthening of the westerlies counteracts part of the warming‐induced decline in the global marine oxygen inventory. A poleward shift of the trade‐westerlies boundary, however, triggers a significant decrease of oxygen in the tropical oxygen minimum zone. In a business‐as‐usual CO2 emission scenario, the poleward shift of the trade‐westerlies boundary and warming‐induced increase in stratification contribute equally to the expansion of suboxic waters in the tropical Pacific.

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Section: Introductionsupporting

confidence: 93%

Simulated effects of southern hemispheric wind changes on the Pacific oxygen minimum zone

Getzlaff

Dietze

Oschlies

2016

Geophysical Research Letters

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“…In this region, the easterly trade winds and upper tropical meridional overturning circulation are both weakened (Figure ; wind change is not shown). The weakened easterly trade winds would reduce the equatorial upwelling, contributing to oxygenation and reducing the hypoxic water volume, as suggested in previous studies [ Deutsch et al , ; Duteil et al , ]. After 1000 years, oxygen‐rich deep waters from the Southern Ocean reduce the hypoxic volume in both experiments.…”

Section: Oxygen and Physical Changessupporting

confidence: 75%

Global deep ocean oxygenation by enhanced ventilation in the Southern Ocean under long‐term global warming

Yamamoto

Abe‐Ouchi

Shigemitsu

et al. 2015

Global Biogeochemical Cycles

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Global warming is expected to decrease ocean oxygen concentrations by less solubility of surface ocean and change in ocean circulation. The associated expansion of the oxygen minimum zone would have adverse impacts on marine organisms and ocean biogeochemical cycles. Oxygen reduction is expected to persist for a thousand years or more, even after atmospheric carbon dioxide stops rising. However, long-term changes in ocean oxygen and circulation are still unclear. Here we simulate multimillennium changes in ocean circulation and oxygen under doubling and quadrupling of atmospheric carbon dioxide, using a fully coupled atmosphere-ocean general circulation model and an offline biogeochemical model. In the first 500 years, global oxygen concentration decreases, consistent with previous studies. Thereafter, however, the oxygen concentration in the deep ocean globally recovers and overshoots at the end of the simulations, despite surface oxygen decrease and weaker Atlantic meridional overturning circulation. This is because, after the initial cessation, the recovery and overshooting of deep ocean convection in the Weddell Sea enhance ventilation and supply oxygen-rich surface waters to deep ocean. Another contributor to deep ocean oxygenation is seawater warming, which reduces the export production and shifts the organic matter remineralization to the upper water column. Our results indicate that the change in ocean circulation in the Southern Ocean potentially drives millennial-scale oxygenation in deep ocean, which is opposite to the centennial-scale global oxygen reduction and general expectation.

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“…Furthermore, in some of them, such as the Eastern Tropical South Pacific, nutrients also appear to be increasing [ Czeschel et al , ]. Although many of these changes are likely due to regional dynamics [ Deutsch et al , ; Duteil et al , ], and to some extent SO wind changes [ Getzlaff et al , ], our results suggest that SO biology could also be playing some role in any changes. However, since there is a time lag between when changes in the SO occur and when this affects oxygen in the tropics (Figures and S7), it is difficult to know how much of an influence changes in the SO have, especially because there are so few historical observations from the SO.…”

Section: Discussionmentioning

confidence: 99%

Southern Ocean biological impacts on global ocean oxygen

Keller

Kriest

Koeve

et al. 2016

Geophysical Research Letters

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Southern Ocean (SO) physical and biological processes are known to have a large impact on global biogeochemistry. However, the role that SO biology plays in determining ocean oxygen concentrations is not completely understood. These dynamics are investigated here by shutting off SO biology in two marine biogeochemical models. The results suggest that SO biological processes reduce the ocean's oxygen content, mainly in the deep ocean, by 14 to 19%. However, since these processes also trap nutrients that would otherwise be transported northward to fuel productivity and subsequent organic matter export, consumption, and the accompanying oxygen consumption in midlatitude to low‐latitude waters, SO biology helps to maintain higher oxygen concentrations in these subsurface waters. Thereby, SO biology can influence the size of the tropical oxygen minimum zones. As a result of ocean circulation the link between SO biological processes and remote oxygen changes operates on decadal to centennial time scales.

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Variability in subtropical‐tropical cells drives oxygen levels in the tropical Pacific Ocean

Cited by 44 publications

References 33 publications

Simulated effects of southern hemispheric wind changes on the Pacific oxygen minimum zone

Simulated effects of southern hemispheric wind changes on the Pacific oxygen minimum zone

Global deep ocean oxygenation by enhanced ventilation in the Southern Ocean under long‐term global warming

Southern Ocean biological impacts on global ocean oxygen

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