Climate Dynamics

, Volume 41, Issue 5, pp 1439–1452

Importance of oceanic resolution and mean state on the extra-tropical response to El Niño in a matrix of coupled models

  • Andrew Dawson
  • Adrian J. Matthews
  • David P. Stevens
  • Malcolm J. Roberts
  • Pier Luigi Vidale
Article

DOI: 10.1007/s00382-012-1518-6

Cite this article as:
Dawson, A., Matthews, A.J., Stevens, D.P. et al. Clim Dyn (2013) 41: 1439. doi:10.1007/s00382-012-1518-6

Abstract

The extra-tropical response to El Niño in configurations of a coupled model with increased horizontal resolution in the oceanic component is shown to be more realistic than in configurations with a low resolution oceanic component. This general conclusion is independent of the atmospheric resolution. Resolving small-scale processes in the ocean produces a more realistic oceanic mean state, with a reduced cold tongue bias, which in turn allows the atmospheric model component to be forced more realistically. A realistic atmospheric basic state is critical in order to represent Rossby wave propagation in response to El Niño, and hence the extra-tropical response to El Niño. Through the use of high and low resolution configurations of the forced atmospheric-only model component we show that, in isolation, atmospheric resolution does not significantly affect the simulation of the extra-tropical response to El Niño. It is demonstrated, through perturbations to the SST forcing of the atmospheric model component, that biases in the climatological SST field typical of coupled model configurations with low oceanic resolution can account for the erroneous atmospheric basic state seen in these coupled model configurations. These results highlight the importance of resolving small-scale oceanic processes in producing a realistic large-scale mean climate in coupled models, and suggest that it might may be possible to “squeeze out” valuable extra performance from coupled models through increases to oceanic resolution alone.

Keywords

North Pacific Extra-tropical SST ENSO GCM Basic state 

Copyright information

© Springer-Verlag 2012

Authors and Affiliations

  • Andrew Dawson
    • 1
    • 5
  • Adrian J. Matthews
    • 1
    • 2
  • David P. Stevens
    • 1
  • Malcolm J. Roberts
    • 3
  • Pier Luigi Vidale
    • 4
  1. 1.School of MathematicsUniversity of East AngliaNorwichUK
  2. 2.School of Environmental SciencesUniversity of East AngliaNorwichUK
  3. 3.Met Office Hadley CentreExeterUK
  4. 4.Department of Meteorology, National Centre for Atmospheric ScienceUniversity of ReadingReadingUK
  5. 5.Atmospheric, Oceanic and Planetary Physics, Department of PhysicsUniversity of OxfordOxfordUK

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