Modeling interaction of a tropical cyclone with its cold wake

Abstract

This dissertation examines the tropical cyclone (TC) intensity response to its cold wake first with five idealized cold wakes using an uncoupled version of the Coupled Ocean/Atmosphere Mesoscale Modeling System for Tropical Cyclone (COAMPS-TC) and then with simulated cold wakes from the coupled version. These simulations reveal a new dynamical pathway induced by the ocean cold wake that acts in concert with the conventional thermodynamic pathway to modulate the TC structure and intensity change. Wakes with a long trailing part or an irregular shape below the eyewall region force a dynamic response that tends to offset the negative feedback effect of reduced enthalpy flux. In particular, a low-level jet-like feature referred to as the wake jet is found at the top of the atmospheric boundary layer above the trailing cold wake. Significant wake cooling underneath the eye also tends to damp the vorticity gradient in the eyewall region, which forces the eyewall to transition from an unstable ring vortex to a stable Rankine-like vortex.