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Climate Dynamics

, Volume 8, Issue 3, pp 103–116 | Cite as

Century-scale variability in a randomly forced, two-dimensional thermohaline ocean circulation model

  • L A Mysak
  • T F Stocker
  • F Huang
Article

Abstract

The response of a two-dimensional thermohaline ocean circulation model to a random freshwater flux superimposed on the usual mixed boundary conditions for temperature and salinity is considered. It is shown that for a wide range of vertical and horizontal diffusivities and a box geometry that approximates the Atlantic Ocean, 200–300 yr period oscillations exist in the basic-state, interhemispheric meridional overturning circulation with deep convection in the north. These fluctuations can also be described in terms of propagating salinity anomalies which travel in the direction of the thermohaline flow. For large horizontal (K h = 15 × 103 m2/s) and small vertical (K v = 0.5 × 10−4 m2/s) diffusivities, the random forcing also excites deca-millennial oscillations in the basic structure of the thermohaline circulation. In this case, the meridional circulation pattern slowly oscillates between three different stages: a large positive cell, with deep convection in the North Atlantic and upwelling in the south; a symmetric two-cell circulation, with deep convection in both polar regions and upwelling near the equator; and a large negative cell, with deep convection in the South Atlantic and upwelling in the north. Each state can persist for 0 (10 kyr).

Keywords

Atlantic Ocean Basic Structure Polar Region Period Oscillation Circulation Pattern 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer-Verlag 1993

Authors and Affiliations

  • L A Mysak
    • 1
  • T F Stocker
    • 1
  • F Huang
    • 1
  1. 1.Department of Atmospheric and Oceanic Sciences and Centre for Climate and Global Change ResearchMcGill UniversityMontrealCanada

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