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Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean
- Source :
- Biogeosciences, Vol 15, Pp 7111-7126 (2018)
- Publication Year :
- 2018
- Publisher :
- Copernicus Publications, 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.
Details
- Language :
- English
- ISSN :
- 17264170 and 17264189
- Volume :
- 15
- Database :
- Directory of Open Access Journals
- Journal :
- Biogeosciences
- Publication Type :
- Academic Journal
- Accession number :
- edsdoj.fe34e4938c4a4b87070093f9d6c836
- Document Type :
- article
- Full Text :
- https://doi.org/10.5194/bg-15-7111-2018