The meganism behind internally generated centennial-to-millennial scale climate variability in an earth system model of intermediate complexity

T. Friedrich, A. Timmermann, L. Menviel, O. Elison Timm, A. Mouchet, D.M.V.A.P. Roche

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    Abstract

    The mechanism triggering centennial-to-millennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) in the earth system model of intermediate complexity LOVECLIM is investigated. It is found that for several climate boundary conditions such as low obliquity values (∼22.1 ) or LGM-albedo, internally generated centennial-to-millennial-scale variability occurs in the North Atlantic region. Stochastic excitations of the density-driven overturning circulation in the Nordic Seas can create regional sea-ice anomalies and a subsequent reorganization of the atmospheric circulation. The resulting remote atmospheric anomalies over the Hudson Bay can release freshwater pulses into the Labrador Sea and significantly increase snow fall in this region leading to a subsequent reduction of convective activity. The millennial-scale AMOC oscillations disappear if LGM bathymetry (with closed Hudson Bay) is prescribed or if freshwater pulses are suppressed artificially. Furthermore, our study documents the process of the AMOC recovery as well as the global marine and terrestrial carbon cycle response to centennial-to- millennial-scale AMOC variability. © 2012 Author(s).
    Original languageEnglish
    Pages (from-to)377-389
    Number of pages13
    JournalGeoscientific Model Development
    Volume3
    Issue number2
    DOIs
    Publication statusPublished - 2010

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