Mechanism of broad spectrum of variabilities in the tropics

The hierarchy of temporal organizations that reveals itself as a broad spectrum of quasi‐periodic oscillations plays important roles in dynamics and predictability in the tropics. We show here that this broad spectrum of oscillations is a response of the tropical circulation to convective internal dynamics modulated by Sea Surface Temperature (SST) and mean conditions. We explore this scenario through a model describing the horizontal dynamics of the first baroclinic mode on an equatorial β ‐plane. The highlight of the formulation is inclusion of a convective relaxation time scale that governs the convective heating. The initial fields, SST and the mean wind are obtained from COADS. The model exhibits periodicities at several observed time scales and many of their spatio‐temporal features. The present study can thus help to formulate appropriate convective schemes in large‐scale models.