Large-Scale Dynamics of Tropical Cyclone Formation Associated with ITCZ Breakdown

This study examines the formation of tropical cyclones (TCs) from the large-scale dynamical perspective. Using the recent advance in nonlinear dynamical transition, it is shown that the large-scale formation of TCs can be understood as a result of the principle of exchange of stabilities in the Intertropical Convergence Zone (ITCZ) breakdown model. Analyses of the transition dynamics at the critical point reveal that the maximum number of TC disturbances that the Earth's tropical atmosphere can support at any instant of time has an upper bound, which is <12 for current atmospheric conditions. Further numerical analyses on the central manifold of this ITCZ breakdown model confirms this important finding, which offers an explanation for a fundamental question of why the Earth's atmosphere can support a limited number of TCs globally each year.