the Creative Commons Attribution 3.0 License.
the Creative Commons Attribution 3.0 License.
Orbital modulation of millennial-scale climate variability in an earth system model of intermediate complexity
T. Friedrich
A. Timmermann
O. Timm
A. Mouchet
D. M. Roche
Abstract. The effect of orbital variations on simulated millennial-scale variability of the Atlantic Meridional Overturning Circulation (AMOC) is studied using the earth system model of intermediate complexity LOVECLIM. It is found that for present-day topographic boundary conditions low obliquity values (~22.1°) favor the triggering of internally generated millennial-scale variability in the North Atlantic region. Reducing the obliquity leads to changes of the pause-pulse ratio of the corresponding AMOC oscillations. 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 leading to a subsequent reduction of convective activity. The millennial-scale AMOC oscillations disappear if LGM bathymetry (with closed Hudson Bay) is prescribed. Furthermore, our study documents the marine and terrestrial carbon cycle response to millennial-scale AMOC variability. Our model results support the notion that stadial regimes in the North Atlantic are accompanied by relatively high levels of oxygen in thermocline and intermediate waters off California – in agreement with paleo-proxy data.
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T. Friedrich et al.


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RC C674: 'Review', Anonymous Referee #1, 15 Sep 2009
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RC C688: 'Review', Anonymous Referee #2, 18 Sep 2009
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AC C919: 'Response to Reviewers' Comments', Tobias Friedrich, 12 Nov 2009


-
RC C674: 'Review', Anonymous Referee #1, 15 Sep 2009
-
RC C688: 'Review', Anonymous Referee #2, 18 Sep 2009
-
AC C919: 'Response to Reviewers' Comments', Tobias Friedrich, 12 Nov 2009
T. Friedrich et al.
T. Friedrich et al.
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Cited
5 citations as recorded by crossref.
- Fine scale sediment structure and geochemical signature between eastern and western North Atlantic during Heinrich events 1 and 2 H. Rashid et al. 10.1016/j.quascirev.2012.04.026
- Patterns of millennial variability over the last 500 ka M. Siddall et al. 10.5194/cp-6-295-2010
- Factors controlling the last interglacial climate as simulated by LOVECLIM1.3 M. Loutre et al. 10.5194/cp-10-1541-2014
- Millennial and sub-millennial scale climatic variations recorded in polar ice cores over the last glacial period E. Capron et al. 10.5194/cp-6-345-2010
- Modelling glacial climatic millennial-scale variability related to changes in the Atlantic meridional overturning circulation: a review M. Kageyama et al. 10.1016/j.quascirev.2010.05.029