the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific
Abstract. The El Niño Southern Oscillation (ENSO) with its warm (El Niño) and cold (La Niña) phase has strong impacts on marine ecosystems off Peru. This influence extends from changes in nutrient availability to productivity and oxygen levels. While several studies have demonstrated the influence of ENSO events on biological productivity, less is known about their impact on oxygen concentrations. In situ observations along the Peruvian and Chilean coast have shown a strong water column oxygenation during the 1997/1998 strong El Niño event. These observations suggest a deepening of the oxygen minimum zone (OMZ) along the continental shelf. However, due to reduced spatial coverage of the existing in situ observations, no studies have yet demonstrated the OMZ response to El Niño events in the whole Eastern Tropical South Pacific (ETSP). Furthermore, most studies have focused on El Niño events. Much less attention was given to the oxygen dynamics under La Niña influence. Here, we provide a comprehensive analysis of the ENSO influence on OMZ dynamics. Interannual variability of the OMZ during the period 1990–2010 is derived from a regional coupled physical-biogeochemical model forced with realistic atmospheric and lateral boundary conditions. Our results show a reduction of the vertical extent and a deepening of suboxic waters (SW) during the El Niño phase. During the La Niña phase, there is a vertical expansion of SW. These fluctuations in OMZ extent are due to changes in oxygen supply into its core depth mainly from lateral margins. During the El Niño phase, the enhanced lateral oxygen supply from the subtropics is the main reason for the reduction of SW in both coastal and offshore regions. During the La Niña phase, the oxygenated subtropical waters are blocked by the poleward transport along the southern margin of the OMZ. Consequently, oxygen concentrations within the OMZ are reduced and suboxic conditions expand during La Niña. The detailed analysis of transport pathways presented here provides new insights into how ENSO variability affects the oxygen-sensitive marine biogeochemistry of the ETSP.
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SC1: 'Evidence of a previous paper on the impact of El Nino events on oxygen in the Peru upwelling system', Vincent Echevin, 09 May 2019
- AC1: 'Answer to 'Evidence of a previous paper on the impact of El Nino events on oxygen in the Peru upwelling system'', Yonss José, 16 May 2019
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RC1: 'Review for
José, Y. S., Stramma, L., Schmidtko, S., and Oschlies, A.: ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific', Anonymous Referee #1, 31 May 2019
- AC2: 'Response to reviewer 1 comments', Yonss José, 05 Dec 2019
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RC2: '# Review: "ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific" by Saranga et al.', Anonymous Referee #2, 05 Jun 2019
- AC3: 'response to reviewer 2 comments', Yonss José, 05 Dec 2019
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RC3: 'Review of “ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific” by Saranga José et al., for Biogeosciences', Anonymous Referee #3, 17 Jun 2019
- AC4: 'response to reviewer 3 comments', Yonss José, 05 Dec 2019
-
SC1: 'Evidence of a previous paper on the impact of El Nino events on oxygen in the Peru upwelling system', Vincent Echevin, 09 May 2019
- AC1: 'Answer to 'Evidence of a previous paper on the impact of El Nino events on oxygen in the Peru upwelling system'', Yonss José, 16 May 2019
-
RC1: 'Review for
José, Y. S., Stramma, L., Schmidtko, S., and Oschlies, A.: ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific', Anonymous Referee #1, 31 May 2019
- AC2: 'Response to reviewer 1 comments', Yonss José, 05 Dec 2019
-
RC2: '# Review: "ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific" by Saranga et al.', Anonymous Referee #2, 05 Jun 2019
- AC3: 'response to reviewer 2 comments', Yonss José, 05 Dec 2019
-
RC3: 'Review of “ENSO-driven fluctuations in oxygen supply and vertical extent of oxygen-poor waters in the oxygen minimum zone of the Eastern Tropical South Pacific” by Saranga José et al., for Biogeosciences', Anonymous Referee #3, 17 Jun 2019
- AC4: 'response to reviewer 3 comments', Yonss José, 05 Dec 2019
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Cited
3 citations as recorded by crossref.
- Emergent constraint on oxygenation of the upper South Eastern Pacific oxygen minimum zone in the twenty-first century I. Almendra et al. 10.1038/s43247-024-01427-2
- On the interpretation of changes in the subtropical oxygen minimum zone volume off Chile during two La Niña events (2001 and 2007) M. Pizarro-Koch et al. 10.3389/fmars.2023.1155932
- Diving deeper: Mesopelagic fish biomass estimates comparison using two different models M. Hill Cruz et al. 10.3389/fmars.2023.1121569