Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean.

Duteil, Olaf, Oschlies, Andreas and Böning, Claus W. (2018) Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean. Open Access Biogeosciences (BG), 15 . pp. 7111-7126. DOI 10.5194/bg-15-7111-2018.

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Abstract

The impact of the positive and negative phases of the Pacific Decadal Oscillation (PDO) on the extension of the poorly oxygenated regions of the eastern Pacific Ocean was assessed using a coupled ocean circulation–biogeochemical model. We show that during a “typical” PDO-positive phase the volume of the suboxic regions expands by 7 % over 50 years due to a slowdown of the large-scale circulation related to the decrease in the intensity of the trade winds. Changes in oxygen levels are mostly controlled by advective processes between 10∘ N and 10∘ S, whereas diffusive processes are dominant poleward of 10∘: in a “typical” PDO-positive phase the sluggish equatorial current system provides less oxygen to the eastern equatorial part of the basin while the oxygen transport by diffusive processes significantly decreases south of 10∘ S. The suboxic region located north of 10∘ N displays less sensitivity to the phase of the PDO as the local upwelling-related processes play a dominant role compared to the large-scale circulation in setting the oxygen concentration. Our study suggests that the prevailing PDO-positive conditions since 1975 may explain a significant part of the current deoxygenation occurring in the eastern Pacific Ocean.

Document Type: Article
Research affiliation: OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-BM Biogeochemical Modeling
OceanRep > SFB 754
OceanRep > SFB 754 > A2
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-TM Theory and Modeling
Refereed: Yes
Open Access Journal?: Yes
DOI etc.: 10.5194/bg-15-7111-2018
ISSN: 1726-4170
Related URLs:
Projects: SFB754
Date Deposited: 19 Jan 2018 07:47
Last Modified: 17 Jan 2019 13:34
URI: http://oceanrep.geomar.de/id/eprint/41656

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