Model Simulation of the NAO

Can current generation climate model's capture the observed features of the North Atlantic Oscillation? If so, which features depend on coupled ocean-atmosphere processes and which are purely atmospheric? How much role do land-atmosphere interactions play in the NAO? All these questions and many more can be addressed by running numerical climate models and carefully examining the behaviour of their results.

In contrast to the many El Nino/Southern Oscillation (ENSO) modelling studies, very few published studies have specifically evaluated the ability of climate models to simulate the NAO. Glowienka-Hense (1990) showed that the NAO was realistically simulated by an atmosphere-only general circulation model confirming that NAO is fundamentally caused by atmospheric processes. Several studies have also shown that NAO can be captured quite realistically by coupled ocean-atmosphere models (Pittalwala and Hameed 1991; Osborn et al. 1999). By comparing coupled simulations made using different ocean models, Ulbrich and Christof (1999) demonstrated that the NAO in sea-level pressure variations simulated by ECHAM4 was not sensitive to the choice of ocean model. However, this does not preclude the possibility that the surface temperature response to NAO can depend on the choice of ocean model and coupling scheme.

• The Coupled Model Intercomparison Project
  
  
• The proposed CMIP subproject to assess the modeled NAO: "NAOMIP"
  
  
• Other CMIP subprojects
  
  
• D.B. Stephenson, V. Pavan and participating CMIP1 modeling groups (2002)
  "The North Atlantic Oscillation in coupled climate models: a CMIP1 evaluation"
  Climate Dynamics (revised)
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