Tropical Cyclone Formation

Abstract

In this chapter, precursor synoptic signals prior to tropical cyclone (TC) genesis in the western North Pacific (WNP) is first described, followed by the discussion of origin of the summertime synoptic-scale wave train in the WNP and the energy source and dispersion characteristics of Pacific easterly waves. Next numerical simulations of TC formation are described, with a particular focus on cyclogenesis in the wake of a preexisting TC due to its energy dispersion and the genesis efficiency of an initial mid-level vortex versus an initial bottom vortex. The climatologic aspect of the tropical cyclogenesis is further discussed, with a focus on the large-scale control of the atmospheric intraseasonal oscillation (ISO) and El Niño-Southern Oscillation (ENSO). A methodology is developed to rank key cyclogenesis parameters at tropical Pacific and Atlantic basins. Finally the robust signals of future TC projection in the North Pacific from high-resolution global model simulations are discussed.