Numerical experimentation with a primitive equation model has shown that local eastward moving forcing in the extra-tropics can produce a large response in zonal wind, vertical velocity and temperature in the equatorial region. This has been explained as a resonance with the first baroclinic mode equatorial Kelvin wave. It is proposed that extra-tropical activity could thus lead to an organisation of equatorial convection that is sufficient to initiate an Intra-Seasonal Oscillation (ISO)
Three week primitive equation model runs with specified fixed or moving tropical heating which mimics that occuring in the ISO have been performed. The results suggest that the observed global streamfunction and zonal wind anomalies associated with th ISO can all be associated with the Rossby waves forced by the heating.
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