On the origins of open ocean Oxygen Minimum Zones

Davila, Xabier; Olsen, Are; Lauvset, Siv K.; McDonagh, Elaine L.; Brakstad, Ailin; Gebbie, Geoffrey. 2023 On the origins of open ocean Oxygen Minimum Zones. Journal of Geophysical Research: Oceans, 128 (8). https://doi.org/10.1029/2023JC019677

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Official URL: http://dx.doi.org/10.1029/2023JC019677

Abstract/Summary

Recent work suggests that Oxygen Minimum Zones (OMZs) are sustained by the supply of oxygen-poor waters rather than the export of organic matter from the local surface layer and its subsequent remineralization inside OMZs. However, the mechanisms that form and maintain OMZs are not well constrained, such as the origin of the oxygen that oxygenates OMZs, and the locations where oxygen consumption occurs. Here we use an observation-based transport matrix to determine the origins of open ocean OMZs in terms of (a) OMZ volume, (b) oxygen that survives remineralization and oxygenates OMZs, and (c) oxygen utilization in the interior ocean that contributes to the oxygen-deficit of OMZs. We also determine where the utilization of oxygen occurs along the pathways that ventilate the OMZs. Our results show that about half of the volume of OMZ waters originate in high-latitude regions, but most of their oxygen is utilized for remineralization before they reach OMZs. Instead, OMZs are mostly oxygenated by tropical, subtropical and intermediate waters formed in nearby regions. More than half of the utilization of oxygen occurs in the tropics and subtropics, while less than a third occurs within the OMZs themselves. We therefore suggest that, in steady-state, OMZs are primarily set by ocean circulation pathways that high-latitude deep and old water upwards, with relatively low oxygen content.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2023JC019677
ISSN:	2169-9275
Date made live:	05 Sep 2023 12:19 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/535743

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1029/2023JC019677

ISSN:

2169-9275

Date made live:

05 Sep 2023 12:19 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/535743