CISK Kelvin Wave with Evaporation-Wind Feedback and Air-Sea Interaction A Further Study of Tropical Intraseasonal Oscillation Mechanism

The wave-CISK (cumulus convection heating feedback), the air-sea interaction and the evaporation-wind feedback are together introduced into a simple theoretical model, in order to understand their effect on driving tropical atmospheric intraseasonal oscillation (ISO). The results showed that among the introduced dynamical processes the wave-CISK plays a major role in reducing phase speed of the wave to be closer to the observed tropical ISO. While the evaporation-wind feedback plays a major role in unstabilizing the wave. The air-sea interaction has certain effect on slowing down the phase speed of the wave. Therefore, the wave-CISK and evaporation-wind feedback can be regarded as fundamental dynamical mechanism of the tropical ISO. This study also shows that since the effects of the evaporation-wind feedback and the air-sea interaction were introduced, the excited wave is zonally dispersive, which can dynamically explain the activity feature of the observed ISO in the tropical atmosphere very well.