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          Institute: MPI für Meteorologie     Collection: Ocean in the Earth System     Display Documents

ID: 377564.0, MPI für Meteorologie / Ocean in the Earth System
Interdecadal variability of the Meridional Overturning Circulation as an ocean internal mode
Authors:Zhu, X.; Jungclaus, J. H.
Date of Publication (YYYY-MM-DD):2008
Title of Journal:Climate Dynamics
Start Page:731
End Page:741
Review Status:Peer-review
Audience:Not Specified
Abstract / Description:The meridional overturning circulation (MOC) in the coupled ECHAM5/MPIOM exhibits variability at periods of near 30 years and near 60 years. The 30-year variability, referred to as interdecadal variability (IDV), exist in an ocean model driven by climatological atmospheric forcing, suggesting that it is maintained by ocean dynamics; the 60-year variability, the multidecadal variability (MDV), is only observed in the fully coupled model and therefore is interpreted as an atmosphere–ocean coupled mode. The coexistence of the 30-year IDV and the 60-year MDV provides a possible explanation for the widespread time scales observed in climate variables. Further analyses of the climatologically forced ocean model shows that, the IDV is related to the interplay between the horizontal temperature-dominated density gradients and the ocean circulation: temperature anomalies move along the cyclonic subpolar gyre leading to fluctuations in horizontal density gradients and the subsequent weakening and strengthening of the MOC. This result is consistent with that from less complex models, indicating the robustness of the IDV. We further show that, along the North Atlantic Current path, the sea surface temperature anomalies are determined by the slow LSW advection at the intermediate depth.
Free Keywords:Interdecadal variability - Ocean dynamics - Labrador sea water - North Atlantic current - Meridional overturning circulation
External Publication Status:published
Document Type:Article
Communicated by:Carola Kauhs
Affiliations:MPI für Meteorologie/Ocean in the Earth System
MPI für Meteorologie/IMPRS Earth System Modelling
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