Multiple Quasi Equilibria of the ITCZ and the Origin of Monsoon Onset. Part II: Rotational ITCZ Attractors

Chao's numerical and theoretical work on multiple quasi equilibria of the intertropical convergence zone (ITCZ) and the origin of monsoon onset is extended to solve two additional puzzles. One is the highly nonlinear dependence on latitude of the “force” acting on the ITCZ due to the earth's rotation, which makes the multiple quasi equilibria of the ITCZ and monsoon onset possible. The other is the dramatic difference in such dependence when different cumulus parameterization schemes are used in a model. Such a difference can lead to a switch between a single ITCZ at the equator and a double ITCZ, when a different cumulus parameterization scheme is used. Sometimes one of the double ITCZ can diminish and only the other remains strong, but still this can mean different latitudinal locations for the single ITCZ. A single idea based on two off-equator attractors for the ITCZ symmetric with respect to the equator, due to the earth's rotation, and the dependence of the strength and size of these attrac...