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www.geosci-model-dev.net/3/377/2010/
doi:10.5194/gmd-3-377-2010
© Author(s) 2010. This work is distributed
under the Creative Commons Attribution 3.0 License.
The mechanism behind internally generated centennial-to-millennial scale climate variability in an earth system model of intermediate complexity
1IPRC, University of Hawaii, 2525 Correa Road, Honolulu, HI 96822, USA
2Département Astrophysique, Géophysique et Océanographie, Université de Liège Liège, Belgium
3Section Climate Change and Landscape Dynamics, Department of Earth Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, 1081 HV Amsterdam, Netherlands
*now at: Climate and Environmental Physics, Physics Institute, University of Bern, Bern, Switzerland
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.
Final Revised Paper (PDF, 2664 KB) Discussion Paper (GMDD)
Citation: Friedrich, T., Timmermann, A., Menviel, L., Elison Timm, O., Mouchet, A., and Roche, D. M.: The mechanism behind internally generated centennial-to-millennial scale climate variability in an earth system model of intermediate complexity, Geosci. Model Dev., 3, 377-389, doi:10.5194/gmd-3-377-2010, 2010. Bibtex EndNote Reference Manager XML
