Contributions to tropical cyclone motion by small, medium and large scales in the initial vortex

Abstract

A two-dimensional Fourier decomposition procedure is used to isolate small (≤500 km), medium (500 < λ ≤ 1500 km) and large (>1500 km) scale components of some typical tangential wind profiles used in theoretical studies of tropical cyclone motion. The contribution of these scales to the vortex motion is studied in a nondivergent barotropic model with no initial basic flow. The largest scales, which account for a significant fraction of the vortex structure, primarily determine the speed of motion. The medium and small scales that contain less energy (because of the assumed vortex structure parameters) have a significant effect on the direction of motion by influencing the rotation of the asymmetric gyres that are induced primarily by the largest scales. -from Authors