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Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean.
- Source :
- Biogeosciences; 2018, Vol. 15 Issue 23, p7111-7126, 16p, 4 Graphs, 4 Maps
- Publication Year :
- 2018
-
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. [ABSTRACT FROM AUTHOR]
Details
- Language :
- English
- ISSN :
- 17264170
- Volume :
- 15
- Issue :
- 23
- Database :
- Complementary Index
- Journal :
- Biogeosciences
- Publication Type :
- Academic Journal
- Accession number :
- 133733810
- Full Text :
- https://doi.org/10.5194/bg-15-7111-2018