Major variations in subtropical North Atlantic heat transport at short (5 day) timescales and their causes

Moat, B.I. ORCID: https://orcid.org/0000-0001-8676-7779; Josey, S.A. ORCID: https://orcid.org/0000-0002-1683-8831; Sinha, B.; Blaker, A.T. ORCID: https://orcid.org/0000-0001-5454-0131; Smeed, D.A. ORCID: https://orcid.org/0000-0003-1740-1778; McCarthy, G.; Johns, W.E.; Hirschi, J.-M.; Frajka-Williams, E. ORCID: https://orcid.org/0000-0001-8773-7838; Rayner, D. ORCID: https://orcid.org/0000-0002-2283-4140; Duchez, A.; Coward, A.C. ORCID: https://orcid.org/0000-0002-9111-7700. 2016 Major variations in subtropical North Atlantic heat transport at short (5 day) timescales and their causes. Journal of Geophysical Research: Oceans, 121 (5). 3237-3249. https://doi.org/10.1002/2016JC011660

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	Text Accepted for publication in Journal of Geophysical Research: Oceans. © 2016 American Geophysical Union. Further reproduction or electronic distribution is not permitted. Moat_NEMO26N_rev1.pdf - Accepted Version Restricted to NORA staff only Download (2MB) | Request a copy
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Abstract/Summary

Variability in the North Atlantic ocean heat transport at 26.5°N on short (5-day) timescales is identified and contrasted with different behaviour at monthly intervals using a combination of RAPID/MOCHA/WBTS measurements and the NEMO-LIM2 1/12° ocean circulation/sea ice model. Wind forcing plays the leading role in establishing the heat transport variability through the Ekman transport response of the ocean and the associated driving atmospheric conditions vary significantly with timescale. We find that at 5-day timescales the largest changes in the heat transport across 26.5°N coincide with north-westerly airflows originating over the American land mass that drive strong southward anomalies in the Ekman flow. During these events the northward heat transport reduces by 0.5-1.4 PW. In contrast, the Ekman transport response at longer monthly timescales is smaller in magnitude (up to 0.5 PW) and consistent with expected variations in the leading mode of North Atlantic atmospheric variability, the North Atlantic Oscillation. The north-westerly airflow mechanism can have a prolonged influence beyond the central 5-day timescale and on occasion can reduce the accumulated winter ocean heat transport into the North Atlantic by ∼40%.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1002/2016JC011660
ISSN:	2169-9291
Additional Keywords:	Atlantic Ocean heat transport; Atlantic subtropical gyre; model-data comparison; RAPID mooring array; Ekman Transport
NORA Subject Terms:	Marine Sciences
Date made live:	07 Apr 2016 16:02 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/513402

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