Critical Role of Continental Slopes in Halocline and Eddy Dynamics of the Ekman-Driven Beaufort Gyre
- Creators
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Manucharyan, G. E.
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Isachsen, P. E.
Abstract
The Beaufort Gyre (BG) is a large‐scale bathymetrically constrained circulation driven by a surface Ekman convergence that creates a bowl‐shaped halocline and stores a significant portion of the Arctic Ocean's freshwater. Theoretical studies suggest that in the gyre interior, the halocline is equilibrated by a balance between Ekman pumping and counteracting mesoscale eddy transport energized by baroclinic instability. However, the strongest anticyclonic flows occur over steep continental slopes, and, despite bathymetric slopes being known to influence baroclinic instability, their large‐scale impacts on BG halocline remain unexplored. Here we use an idealized eddy‐resolving BG model to demonstrate that the existence of continental slopes dramatically affects key gyre characteristics leading to deeper halocline, stronger anticyclonic circulation, and prolonged equilibration. Over continental slopes, the magnitude of the Eulerian mean circulation is dramatically reduced due to the Ekman overturning being compensated by the eddy momentum‐driven overturning. The eddy thickness flux overturning associated with lateral salt transport is also weakened over the slopes, indicating a reduction of eddy thickness diffusivity despite the isopycnal slopes being largest there. Using a theoretical halocline model, we demonstrate that it is the localized reduction in eddy diffusivity over continental slopes that is critical in explaining the halocline deepening and prolonged equilibration time. Our results emphasize the need for observational studies of eddy overturning dynamics over continental slopes and the development of slope‐aware mesoscale eddy parameterizations for low‐resolution climate models.
Additional Information
© 2019 American Geophysical Union. Received 1 OCT 2018; Accepted 26 FEB 2019; Accepted article online 12MAR 2019; Published online 16 APR 2019. All information necessary to reproduce the numerical experiments and data analysis is present in the paper and requires the use of publicly available software. G. E. M. acknowledges support from the Stanback Postdoctoral Fellowship at Caltech. P. E. I. was partially funded by grant 221780 (NorSEE) from the Research Council of Norway. This work used the Extreme Science and Engineering Discovery Environment (XSEDE; Towns et al., 2014), which is supported by NSF grant ACI‐1053575. The manuscript benefited from discussions at the annual Forum for Arctic Modeling and Observing Synthesis (FAMOS) funded by the NSF OPP award PLR‐1313614 and PLR‐1203720. The authors thank John Marshall and an anonymous reviewer for their insightful comments.Attached Files
Published - Manucharyan_et_al-2019-Journal_of_Geophysical_Research__Oceans.pdf
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Additional details
- Eprint ID
- 96184
- Resolver ID
- CaltechAUTHORS:20190606-084354650
- Coco and Foster Stanback Postdoctoral Fellowship in Global Environmental Science
- 221780
- Research Council of Norway
- ACI‐1053575
- NSF
- PLR‐1313614
- NSF
- PLR‐1203720
- NSF
- Created
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2019-06-06Created from EPrint's datestamp field
- Updated
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2021-11-16Created from EPrint's last_modified field