Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean
<p>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...
| Main Authors: | , , |
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| Format: | Article |
| Language: | English |
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Copernicus Publications
2018-11-01
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| Series: | Biogeosciences |
| Online Access: | https://www.biogeosciences.net/15/7111/2018/bg-15-7111-2018.pdf |
| _version_ | 1819238682990739456 |
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| author | O. Duteil A. Oschlies C. W. Böning |
| author_facet | O. Duteil A. Oschlies C. W. Böning |
| author_sort | O. Duteil |
| collection | DOAJ |
| description | <p>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<span class="inline-formula"><sup>∘</sup></span> N and
10<span class="inline-formula"><sup>∘</sup></span> S, whereas diffusive processes are dominant poleward of
10<span class="inline-formula"><sup>∘</sup></span>: 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<span class="inline-formula"><sup>∘</sup></span> S. The suboxic region located north of
10<span class="inline-formula"><sup>∘</sup></span> 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.</p> |
| first_indexed | 2024-12-23T13:40:07Z |
| format | Article |
| id | doaj.art-ccfe34e4938c4a4b87070093f9d6c836 |
| institution | Directory Open Access Journal |
| issn | 1726-4170 1726-4189 |
| language | English |
| last_indexed | 2024-12-23T13:40:07Z |
| publishDate | 2018-11-01 |
| publisher | Copernicus Publications |
| record_format | Article |
| series | Biogeosciences |
| spelling | doaj.art-ccfe34e4938c4a4b87070093f9d6c8362022-12-21T17:44:54ZengCopernicus PublicationsBiogeosciences1726-41701726-41892018-11-01157111712610.5194/bg-15-7111-2018Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific OceanO. Duteil0A. Oschlies1C. W. Böning2GEOMAR – Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg. 20, 24103 Kiel, GermanyGEOMAR – Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg. 20, 24103 Kiel, GermanyGEOMAR – Helmholtz Centre for Ocean Research Kiel, Düsternbrooker Weg. 20, 24103 Kiel, Germany<p>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<span class="inline-formula"><sup>∘</sup></span> N and 10<span class="inline-formula"><sup>∘</sup></span> S, whereas diffusive processes are dominant poleward of 10<span class="inline-formula"><sup>∘</sup></span>: 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<span class="inline-formula"><sup>∘</sup></span> S. The suboxic region located north of 10<span class="inline-formula"><sup>∘</sup></span> 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.</p>https://www.biogeosciences.net/15/7111/2018/bg-15-7111-2018.pdf |
| spellingShingle | O. Duteil A. Oschlies C. W. Böning Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean Biogeosciences |
| title | Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean |
| title_full | Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean |
| title_fullStr | Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean |
| title_full_unstemmed | Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean |
| title_short | Pacific Decadal Oscillation and recent oxygen decline in the eastern tropical Pacific Ocean |
| title_sort | pacific decadal oscillation and recent oxygen decline in the eastern tropical pacific ocean |
| url | https://www.biogeosciences.net/15/7111/2018/bg-15-7111-2018.pdf |
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