A minimal model for wind- and mixing-driven overturning: threshold behavior for both driving mechanisms

Johannes Fürst, Anders Levermann, J.-c. Duplessy (Editor), E.k. Schneider (Editor), S. Corti (Editor), B.p. Kirtman (Editor), D.g. Dewitt (Editor)

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


We present a minimal conceptual model for the Atlantic meridional overturning circulation which incorporates the advection of salinity and the basic dynamics of the oceanic pycnocline. Four tracer transport processes following Gnanadesikan (1999) allow for a dynamical adjustment of the oceanic pycnocline which defines the vertical extent of a mid-latitudinal box. At the same time the model captures the salt-advection feedback (Stommel, 1961). Due to its simplicity the model can be solved analytically in the purely wind- and purely mixing-driven cases. We find the possibility of abrupt transition in response to surface freshwater forcing in both cases even though the circulations are very different in physics and geometry. This analytical approach also provides expressions for the critical freshwater input marking the change in the dynamics of the system. Our analysis shows that including the pycnocline dynamics in a salt-advection model causes a decrease in the freshwater sensitivity of its northern sinking up to a threshold at which the circulation breaks down. Compared to previous studies the model is restricted to the essential ingredients. Still, it exhibits a rich behavior which reaches beyond the scope of this study and might be used as a paradigm for the qualitative behaviour of the Atlantic overturning in the discussion of driving mechanisms.
Original languageEnglish
Pages (from-to)239-260
Number of pages22
JournalClimate Dynamics
Issue number1-2
Publication statusPublished - 1 Jan 2012

Bibliographical note

J.-C. Duplessy and E.K. Schneider and S. Corti and B.P. Kirtman and D.G. DeWitt


  • Meridional overturning circulation
  • Northern sinking
  • Critical freshwater threshold
  • Overturning sensitivity
  • Conceptual model
  • Stability
  • Atlantic meridional overturning circulation
  • Pycnocline depth
  • Driving mechanism


Dive into the research topics of 'A minimal model for wind- and mixing-driven overturning: threshold behavior for both driving mechanisms'. Together they form a unique fingerprint.

Cite this