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Font, Estel, Swart, Sebastiaan, Bruss, Gerd, Sheehan, Peter M. F. 
ORCID: https://orcid.org/0000-0002-4906-5724, Heywood, Karen J. ORCID: https://orcid.org/0000-0001-9859-0026 and Queste, Bastien Y.
(2024)
Ventilation of the Arabian Sea oxygen minimum zone by Persian Gulf water.
Journal of Geophysical Research - Oceans, 129 (5).
ISSN 2169-9275
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Abstract
Dense overflows from marginal seas are critical pathways of oxygen supply to the Arabian Sea oxygen minimum zone (OMZ), yet these remain inadequately understood. Climate models struggle to accurately reproduce the observed extent and intensity of the Arabian Sea OMZ due to their limited ability to capture processes smaller than their grid scale, such as dense overflows. Multi-month repeated sections by underwater gliders off the coast of Oman resolve the contribution of dense Persian Gulf Water (PGW) outflow to oxygen supply within the Arabian Sea OMZ. We characterize PGW properties, seasonality, transport and mixing mechanisms to explain local processes influencing water mass transformation and oxygen fluxes into the OMZ. Atmospheric forcing at the source region and eddy mesoscale activity in the Gulf of Oman control spatiotemporal variability of PGW as it flows along-shelf off the northern Omani coast. Subseasonally, it is modulated by stirring and shear-driven mixing driven by eddy-topography interactions. The oxygen transport from PGW to the OMZ is estimated to be 1.3 Tmol yr−1 over the observational period, with dramatic inter- and intra-annual variability (±1.6 Tmol yr−1). We show that this oxygen is supplied to the interior of the OMZ through the combined action of double-diffusive and shear-driven mixing. Intermittent shear-driven mixing enhances double-diffusive processes, with mechanical shear conditions (Ri < 0.25) prevailing 14% of the time at the oxycline. These findings enhance our understanding of fine-scale processes influencing oxygen dynamics within the OMZ that can provide insights for improved modeling and prediction efforts.
| Item Type: | Article |
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| Additional Information: | Funding Information: EF, GB and BYQ are supported by ONR GLOBAL Grant N62909-21-1-2008. EF and BYQ are supported by Formas Grant 2022-01536. EF and SS are supported by a Wallenberg Academy Fellowship (WAF, 2015.0186). SS is supported by the Swedish Research Council (VR, 2019-04400), the European Union\u2019s Horizon 2020 research and innovation programme under Grant 821001 (SO-CHIC). SS and BYQ are supported by European Union\u2019s Horizon 2020 research and innovation programme under Grant 951842 (GROOM II). GB is supported by Sultan Qaboos University grants EG/AGR/FISH/14/01 and IG/AGR/FISH/17/01. BYQ and KH are supported by ONR GLOBAL Grant N62909\u201314-1-N224/SQU. BYQ, PMFS and KJH acknowledge funding support from the European Research Council under the European Union\u2019s Horizon 2020 research and innovation programme (COMPASS, grant agreement n\u00B0 741120). BYQ is supported by UK NERC Grants NE/M005801/1 and NE/N012658/1. We are grateful to the UEA Seaglider Facility, Sultan Qaboos University technical staff and Five Oceans Environmental Services consultancy for their technical help with instrument deployments and recoveries during 2015 and 2016. The authors want to thank the technicians and pilots of Voice of the Ocean foundation for assistance and support during deployments and piloting during 2021 and 2022. We also thank Sultan Qaboos University technician Badar Al Buwiqi and boat captains, for their support during deployments and recoveries during 2021 and 2022. The authors would like to thank the two anonymous reviewers whose constructive comments contributed to the improvement of this manuscript. |
| Uncontrolled Keywords: | adcp,ocean glider,oxygen minimum zones,persian gulf water,transport,ventilation,geochemistry and petrology,geophysics,oceanography,space and planetary science,earth and planetary sciences (miscellaneous),sdg 13 - climate action ,/dk/atira/pure/subjectarea/asjc/1900/1906 |
| Faculty \ School: | Faculty of Science > School of Environmental Sciences University of East Anglia Research Groups/Centres > Theme - ClimateUEA |
| UEA Research Groups: | Faculty of Science > Research Groups > Centre for Ocean and Atmospheric Sciences |
| Related URLs: | |
| Depositing User: | LivePure Connector |
| Date Deposited: | 29 Apr 2024 12:30 |
| Last Modified: | 13 May 2024 08:30 |
| URI: | https://ueaeprints.uea.ac.uk/id/eprint/95037 |
| DOI: | 10.1029/2023JC020668 |
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