A theory of the wind-driven Beaufort Gyre variability
Author Posting. © American Meteorological Society, 2016. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 46 (2016): 3263-3278, doi:10.1175/JPO-D-16-0091.1....
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ftwhoas:oai:darchive.mblwhoilibrary.org:1912/8630 2023-05-15T15:02:02+02:00 A theory of the wind-driven Beaufort Gyre variability Manucharyan, Georgy E. Spall, Michael A. Thompson, Andrew F. 2016-10-20 https://hdl.handle.net/1912/8630 en_US eng American Meteorological Society https://doi.org/10.1175/JPO-D-16-0091.1 Journal of Physical Oceanography 46 (2016): 3263-3278 https://hdl.handle.net/1912/8630 doi:10.1175/JPO-D-16-0091.1 Journal of Physical Oceanography 46 (2016): 3263-3278 doi:10.1175/JPO-D-16-0091.1 Arctic Eddies Ekman pumping/transport Large-scale motions Ocean circulation Stability Article 2016 ftwhoas https://doi.org/10.1175/JPO-D-16-0091.1 2022-05-28T22:59:48Z Author Posting. © American Meteorological Society, 2016. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 46 (2016): 3263-3278, doi:10.1175/JPO-D-16-0091.1. 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 m2 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. GEMacknowledges the support from theHowland Postdoctoral Program Fund at WHOI and the Stanback Fellowship Fund at Caltech.MAS was supported by NSF Grants PLR-1415489 and OCE-1232389. AFT acknowledges support from NASA Award NNN12AA01C. 2017-04-20 Article in Journal/Newspaper Arctic Arctic Ocean Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) Arctic Arctic Ocean Journal of Physical Oceanography 46 11 3263 3278 |
institution |
Open Polar |
collection |
Woods Hole Scientific Community: WHOAS (Woods Hole Open Access Server) |
op_collection_id |
ftwhoas |
language |
English |
topic |
Arctic Eddies Ekman pumping/transport Large-scale motions Ocean circulation Stability |
spellingShingle |
Arctic Eddies Ekman pumping/transport Large-scale motions Ocean circulation Stability Manucharyan, Georgy E. Spall, Michael A. Thompson, Andrew F. A theory of the wind-driven Beaufort Gyre variability |
topic_facet |
Arctic Eddies Ekman pumping/transport Large-scale motions Ocean circulation Stability |
description |
Author Posting. © American Meteorological Society, 2016. This article is posted here by permission of American Meteorological Society for personal use, not for redistribution. The definitive version was published in Journal of Physical Oceanography 46 (2016): 3263-3278, doi:10.1175/JPO-D-16-0091.1. 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 m2 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. GEMacknowledges the support from theHowland Postdoctoral Program Fund at WHOI and the Stanback Fellowship Fund at Caltech.MAS was supported by NSF Grants PLR-1415489 and OCE-1232389. AFT acknowledges support from NASA Award NNN12AA01C. 2017-04-20 |
format |
Article in Journal/Newspaper |
author |
Manucharyan, Georgy E. Spall, Michael A. Thompson, Andrew F. |
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://hdl.handle.net/1912/8630 |
geographic |
Arctic Arctic Ocean |
geographic_facet |
Arctic Arctic Ocean |
genre |
Arctic Arctic Ocean |
genre_facet |
Arctic Arctic Ocean |
op_source |
Journal of Physical Oceanography 46 (2016): 3263-3278 doi:10.1175/JPO-D-16-0091.1 |
op_relation |
https://doi.org/10.1175/JPO-D-16-0091.1 Journal of Physical Oceanography 46 (2016): 3263-3278 https://hdl.handle.net/1912/8630 doi:10.1175/JPO-D-16-0091.1 |
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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1766334031332376576 |