nerc.ac.uk

Intrinsic variability of the Atlantic Meridional Overturning Circulation at interannual-to-multidecadal time scales

Grégorio, Sandy; Penduff, Thierry; Sérazin, Guillaume; Molines, Jean-Marc; Barnier, Bernard; Hirschi, Joel. 2015 Intrinsic variability of the Atlantic Meridional Overturning Circulation at interannual-to-multidecadal time scales. Journal of Physical Oceanography, 45 (7). 1929-1946. 10.1175/JPO-D-14-0163.1

Before downloading, please read NORA policies.
[thumbnail of jpo-d-14-0163%2E1.pdf]
Preview
Text
© Copyright 2015 American Meteorological Society (AMS). Permission to use figures, tables, and brief excerpts from this work in scientific and educational works is hereby granted provided that the source is acknowledged. Any use of material in this work that is determined to be “fair use” under Section 107 of the U.S. Copyright Act September 2010 Page 2 or that satisfies the conditions specified in Section 108 of the U.S. Copyright Act (17 USC §108, as revised by P.L. 94-553) does not require the AMS’s permission. Republication, systematic reproduction, posting in electronic form, such as on a web site or in a searchable database, or other uses of this material, except as exempted by the above statement, requires written permission or a license from the AMS. Additional details are provided in the AMS Copyright Policy, available on the AMS Web site located at (http://www.ametsoc.org/) or from the AMS at 617- 227-2425 or copyrights@ametsoc.org.
jpo-d-14-0163%2E1.pdf - Published Version

Download (4MB) | Preview

Abstract/Summary

The low-frequency variability of the Atlantic meridional overturning circulation (AMOC) is investigated from 2, ¼°, and ° global ocean–sea ice simulations, with a specific focus on its internally generated (i.e., “intrinsic”) component. A 327-yr climatological ¼° simulation, driven by a repeated seasonal cycle (i.e., a forcing devoid of interannual time scales), is shown to spontaneously generate a significant fraction R of the interannual-to-decadal AMOC variance obtained in a 50-yr “fully forced” hindcast (with reanalyzed atmospheric forcing including interannual time scales). This intrinsic variance fraction R slightly depends on whether AMOCs are computed in geopotential or density coordinates, and on the period considered in the climatological simulation, but the following features are quite robust when mesoscale eddies are simulated (at both ¼° and ° resolutions); R barely exceeds 5%–10% in the subpolar gyre but reaches 30%–50% at 34°S, up to 20%–40% near 25°N, and 40%–60% near the Gulf Stream. About 25% of the meridional heat transport interannual variability is attributed to intrinsic processes at 34°S and near the Gulf Stream. Fourier and wavelet spectra, built from the 327-yr ¼° climatological simulation, further indicate that spectral peaks of intrinsic AMOC variability (i) are found at specific frequencies ranging from interannual to multidecadal, (ii) often extend over the whole meridional scale of gyres, (iii) stochastically change throughout these 327 yr, and (iv) sometimes match the spectral peaks found in the fully forced hindcast in the North Atlantic. Intrinsic AMOC variability is also detected at multidecadal time scales, with a marked meridional coherence between 35°S and 25°N (15–30 yr periods) and throughout the whole basin (50–90-yr periods).

Item Type: Publication - Article
Digital Object Identifier (DOI): 10.1175/JPO-D-14-0163.1
ISSN: 0022-3670
NORA Subject Terms: Marine Sciences
Date made live: 11 Aug 2015 13:19 +0 (UTC)
URI: https://nora.nerc.ac.uk/id/eprint/511503

Actions (login required)

View Item View Item

Document Downloads

Downloads for past 30 days

Downloads per month over past year

More statistics for this item...