There are a number of explanations of the asymmetry of the Intertropical Convergence Zone (ITCZ), known by sailors as the Doldrums.
Due to the relatively small scale and deep thermocline in the Indian Ocean, there will be less asymmetric effects.
In the middle latitude Pacific and Atlantic Ocean, because of the large scale easterly wind system and the western continents boundaries, the thermocline is definitely shallower in eastern part.
The asymmetry of ITCZ is triggered by the asymmetric SST distribution, which has been verified by General Circulation Model (GCM).
[8] To explain this simply, upwelling brings cold water to the surface, which will cool the above atmosphere and make it stable because of relative high air density due to low temperature.