Abstract
An example of tropical cyclone (TC) formation processes described by a 20-km grid model is presented. A numerical time integration is performed for more than 200 days under a simplified (idealized) condition. Among many TCs that form in this period, this paper describes a TC that forms from a band-shaped meso-α-scale convective system in a westerly flow to the south of the previous TC. The orientation of the mesoscale system is northeast-southwest at the early stage. This orientation is nearly perpendicular to the vertical shear vector of the environmental low-level flow. Strong latent instability is located at the northwestern side of the system, and lower temperatures near the surface (cold pool) is at the southeastern side. This system rotates cyclonically. A center of cyclonic flow, which is located far to the north of the convective system at the early stage, is forced to approach the system, and the wind is intensified by convective activity. When the orientation of the convective system becomes west-east, the system attains TC intensity. Behavior of mesoscale cells which constitute the mesoscale system is also described.
