A Theory of the Wind-Driven Beaufort Gyre Variability
The halocline of the Beaufort Gyre varies significantly on interannual to decadal time scales, affecting the freshwater content (FWC) of the Arctic Ocean. This study explores the role of eddies in the Ekman-driven gyre variability. Following the transformed Eulerian-mean paradigm, the authors develo...
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American Meteorological Society
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ftcaltechauth:oai:authors.library.caltech.edu:73130 2023-05-15T15:08:46+02:00 A Theory of the Wind-Driven Beaufort Gyre Variability Manucharyan, Georgy E. Spall, Michael A. Thompson, Andrew F. 2016-11 application/pdf https://authors.library.caltech.edu/73130/ https://authors.library.caltech.edu/73130/1/jpo-d-16-0091.1.pdf https://resolver.caltech.edu/CaltechAUTHORS:20161222-091517006 en eng American Meteorological Society https://authors.library.caltech.edu/73130/1/jpo-d-16-0091.1.pdf Manucharyan, Georgy E. and Spall, Michael A. and Thompson, Andrew F. (2016) A Theory of the Wind-Driven Beaufort Gyre Variability. Journal of Physical Oceanography, 46 (11). pp. 3263-3278. ISSN 0022-3670. doi:10.1175/JPO-D-16-0091.1. https://resolver.caltech.edu/CaltechAUTHORS:20161222-091517006 <https://resolver.caltech.edu/CaltechAUTHORS:20161222-091517006> other Article PeerReviewed 2016 ftcaltechauth https://doi.org/10.1175/JPO-D-16-0091.1 2021-11-18T18:40:15Z The halocline of the Beaufort Gyre varies significantly on interannual to decadal time scales, affecting the freshwater content (FWC) of the Arctic Ocean. This study explores the role of eddies in the Ekman-driven gyre variability. Following the transformed Eulerian-mean paradigm, the authors develop a theory that links the FWC variability to the stability of the large-scale gyre, defined as the inverse of its equilibration time. The theory, verified with eddy-resolving numerical simulations, demonstrates that the gyre stability is explicitly controlled by the mesoscale eddy diffusivity. An accurate representation of the halocline dynamics requires the eddy diffusivity of 300 ± 200 m^2 s^(−1), which is lower than what is used in most low-resolution climate models. In particular, on interannual and longer time scales the eddy fluxes and the Ekman pumping provide equally important contributions to the FWC variability. However, only large-scale Ekman pumping patterns can significantly alter the FWC, with spatially localized perturbations being an order of magnitude less efficient. Lastly, the authors introduce a novel FWC tendency diagnostic—the Gyre Index—that can be conveniently calculated using observations located only along the gyre boundaries. Its strong predictive capabilities, assessed in the eddy-resolving model forced by stochastic winds, suggest that the Gyre Index would be of use in interpreting FWC evolution in observations as well as in numerical models. Article in Journal/Newspaper Arctic Arctic Ocean Caltech Authors (California Institute of Technology) Arctic Arctic Ocean Journal of Physical Oceanography 46 11 3263 3278 |
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Open Polar |
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Caltech Authors (California Institute of Technology) |
op_collection_id |
ftcaltechauth |
language |
English |
description |
The halocline of the Beaufort Gyre varies significantly on interannual to decadal time scales, affecting the freshwater content (FWC) of the Arctic Ocean. This study explores the role of eddies in the Ekman-driven gyre variability. Following the transformed Eulerian-mean paradigm, the authors develop a theory that links the FWC variability to the stability of the large-scale gyre, defined as the inverse of its equilibration time. The theory, verified with eddy-resolving numerical simulations, demonstrates that the gyre stability is explicitly controlled by the mesoscale eddy diffusivity. An accurate representation of the halocline dynamics requires the eddy diffusivity of 300 ± 200 m^2 s^(−1), which is lower than what is used in most low-resolution climate models. In particular, on interannual and longer time scales the eddy fluxes and the Ekman pumping provide equally important contributions to the FWC variability. However, only large-scale Ekman pumping patterns can significantly alter the FWC, with spatially localized perturbations being an order of magnitude less efficient. Lastly, the authors introduce a novel FWC tendency diagnostic—the Gyre Index—that can be conveniently calculated using observations located only along the gyre boundaries. Its strong predictive capabilities, assessed in the eddy-resolving model forced by stochastic winds, suggest that the Gyre Index would be of use in interpreting FWC evolution in observations as well as in numerical models. |
format |
Article in Journal/Newspaper |
author |
Manucharyan, Georgy E. Spall, Michael A. Thompson, Andrew F. |
spellingShingle |
Manucharyan, Georgy E. Spall, Michael A. Thompson, Andrew F. A Theory of the Wind-Driven Beaufort Gyre Variability |
author_facet |
Manucharyan, Georgy E. Spall, Michael A. Thompson, Andrew F. |
author_sort |
Manucharyan, Georgy E. |
title |
A Theory of the Wind-Driven Beaufort Gyre Variability |
title_short |
A Theory of the Wind-Driven Beaufort Gyre Variability |
title_full |
A Theory of the Wind-Driven Beaufort Gyre Variability |
title_fullStr |
A Theory of the Wind-Driven Beaufort Gyre Variability |
title_full_unstemmed |
A Theory of the Wind-Driven Beaufort Gyre Variability |
title_sort |
theory of the wind-driven beaufort gyre variability |
publisher |
American Meteorological Society |
publishDate |
2016 |
url |
https://authors.library.caltech.edu/73130/ https://authors.library.caltech.edu/73130/1/jpo-d-16-0091.1.pdf https://resolver.caltech.edu/CaltechAUTHORS:20161222-091517006 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean |
genre_facet |
Arctic Arctic Ocean |
op_relation |
https://authors.library.caltech.edu/73130/1/jpo-d-16-0091.1.pdf Manucharyan, Georgy E. and Spall, Michael A. and Thompson, Andrew F. (2016) A Theory of the Wind-Driven Beaufort Gyre Variability. Journal of Physical Oceanography, 46 (11). pp. 3263-3278. ISSN 0022-3670. doi:10.1175/JPO-D-16-0091.1. https://resolver.caltech.edu/CaltechAUTHORS:20161222-091517006 <https://resolver.caltech.edu/CaltechAUTHORS:20161222-091517006> |
op_rights |
other |
op_doi |
https://doi.org/10.1175/JPO-D-16-0091.1 |
container_title |
Journal of Physical Oceanography |
container_volume |
46 |
container_issue |
11 |
container_start_page |
3263 |
op_container_end_page |
3278 |
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1766340064905789440 |