AMOC sensitivity to surface buoyancy fluxes: Stronger ocean meridional heat transport with a weaker volume transport?

doi:10.1007/s00382-015-2915-4

Title: AMOC sensitivity to surface buoyancy fluxes: Stronger ocean meridional heat transport with a weaker volume transport?

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Abstract

Oceanic northward heat transport is commonly assumed to be positively correlated with the Atlantic meridional overturning circulation (AMOC). For example, in numerical "water-hosing" experiments, imposing anomalous freshwater fluxes in the northern Atlantic leads to a slow-down of the AMOC and the corresponding reduction of oceanic northward heat transport. Here, we study the sensitivity of the ocean heat and volume transports to surface heat and freshwater fluxes using a generalized stability analysis. For the sensitivity to surface freshwater fluxes, we find that, while the direct relationship between the AMOC volume and heat transports holds on shorter time scales, it can reverse on timescales longer than 500 years or so. That is, depending on the model surface boundary conditions, reduction in the AMOC volume transport can potentially lead to a stronger heat transport on long timescales, resulting from the gradual increase in ocean thermal stratification. Finally, we discuss the implications of these results for the problem of steady state (statistical equilibrium) in ocean and climate GCM as well as paleoclimate problems including millennial climate variability.

Authors:

Sevellec, Florian ^[1]; Fedorov, Alexey V. ^[2]

Univ. of Southampton (United Kingdom). Ocean and Earth Science, National Oceanography Centre Southampton
Yale Univ., New Haven, CT (United States). Dept. of Geology and Geophysics

Publication Date:: 2016-01-04

Research Org.:: Univ. of Southampton (United Kingdom)

Sponsoring Org.:: USDOE Office of Science (SC)

OSTI Identifier:: 1437164

Grant/Contract Number:: SC0007037

Resource Type:: Accepted Manuscript

Journal Name:: Climate Dynamics

Additional Journal Information:: Journal Volume: 47; Journal Issue: 5-6; Journal ID: ISSN 0930-7575

Publisher:: Springer-Verlag

Country of Publication:: United States

Language:: English

Subject:: 58 GEOSCIENCES; 54 ENVIRONMENTAL SCIENCES; Atlantic meridional overturning circulation; Optimal surface buoyancy fluxes; Ocean dynamics; Adjoint sensitivity analysis

Citation Formats


                    Sevellec, Florian, and Fedorov, Alexey V. AMOC sensitivity to surface buoyancy fluxes: Stronger ocean meridional heat transport with a weaker volume transport?.  United States: N. p., 2016. 
        Web.  doi:10.1007/s00382-015-2915-4.

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                    Sevellec, Florian, & Fedorov, Alexey V. AMOC sensitivity to surface buoyancy fluxes: Stronger ocean meridional heat transport with a weaker volume transport?.  United States.  doi:10.1007/s00382-015-2915-4.

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                    Sevellec, Florian, and Fedorov, Alexey V. Mon .  
        "AMOC sensitivity to surface buoyancy fluxes: Stronger ocean meridional heat transport with a weaker volume transport?".  United States.  doi:10.1007/s00382-015-2915-4.  https://www.osti.gov/servlets/purl/1437164.

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@article{osti_1437164,

  title        = {AMOC sensitivity to surface buoyancy fluxes: Stronger ocean meridional heat transport with a weaker volume transport?},

  author       = {Sevellec, Florian and Fedorov, Alexey V.},

  abstractNote = {Oceanic northward heat transport is commonly assumed to be positively correlated with the Atlantic meridional overturning circulation (AMOC). For example, in numerical "water-hosing" experiments, imposing anomalous freshwater fluxes in the northern Atlantic leads to a slow-down of the AMOC and the corresponding reduction of oceanic northward heat transport. Here, we study the sensitivity of the ocean heat and volume transports to surface heat and freshwater fluxes using a generalized stability analysis. For the sensitivity to surface freshwater fluxes, we find that, while the direct relationship between the AMOC volume and heat transports holds on shorter time scales, it can reverse on timescales longer than 500 years or so. That is, depending on the model surface boundary conditions, reduction in the AMOC volume transport can potentially lead to a stronger heat transport on long timescales, resulting from the gradual increase in ocean thermal stratification. Finally, we discuss the implications of these results for the problem of steady state (statistical equilibrium) in ocean and climate GCM as well as paleoclimate problems including millennial climate variability.},

  doi          = {10.1007/s00382-015-2915-4},

  journal      = {Climate Dynamics},

  number       = 5-6,

  volume       = 47,

  place        = {United States},

  year         = {2016},

  month        = {1}

}

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DOI: 10.1007/s00382-015-2915-4

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