Title: Response of a Strongly Eddying Global Ocean to North Atlantic Freshwater Perturbations

Abstract

The strongly eddying version of the Parallel Ocean Program (POP) is used in two 45-yr simulations to investigate the response of the Atlantic meridional overturning circulation (AMOC) to strongly enhanced freshwater input due to Greenland melting, with an integrated flux of 0.5 Sverdrups (Sv; 1 Sv ≡ 10⁶ m³ s^-1). For comparison, a similar set of experiments is performed using a noneddying version of POP. The aim is to identify the signature of the salt advection feedback in the two configurations. For this reason, surface salinity is not restored in these experiments. The freshwater input leads to a quantitatively comparable reduction of the overturning strength in the two models. To examine the importance of transient effects in the relation between AMOC strength and density distribution, the results of the eddy-resolving model are related to water mass transformation theory. The freshwater forcing leads to a reduction of the rate of light to dense water conversion in the North Atlantic, but there is no change in dense to light transformation elsewhere, implying that high density layers are continuously deflating. The main focus of the paper is on the effect of the AMOC reduction on the basinwide advection of freshwater. The low-resolution modelmore » results show a change of the net freshwater advection that is consistent with the salt advection feedback. However, for the eddy-resolving model, the net freshwater advection into the Atlantic basin appears to be unaffected, despite the significant change in the large-scale velocity structure.« less

Authors:

Toom, Matthijs den ^[1]; Dijkstra, Henk A. ^[1]; Weijer, Wilbert ^[2]; Hecht, Matthew W. ^[2]; Maltrud, Mathew E. ^[2]; van Sebille, Erik ^[3]

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+ Show Author Affiliations

1. Univ. of Utrecht (Netherlands). Dept. of Physics and Astronomy, and Inst. for Marine and Atmospheric Research Utrecht
2. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
3. Univ. of New South Wales, Sydney, NSW (Australia). Climate Change Research Centre, and ARC Centre of Excellence for Climate System Science

Publication Date:

Wed Feb 12 00:00:00 EST 2014

Research Org.:

Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF); Los Alamos National Laboratory (LANL), Los Alamos, NM (United States)

Sponsoring Org.:

USDOE Office of Science (SC)

OSTI Identifier:

1565242

Resource Type:

Accepted Manuscript

Journal Name:

Journal of Physical Oceanography

Additional Journal Information:

Journal Volume: 44; Journal Issue: 2; Journal ID: ISSN 0022-3670

Publisher:

American Meteorological Society

Country of Publication:

United States

Language:

English

Subject:

54 ENVIRONMENTAL SCIENCES; Oceanography