The Role of Convective Heating in the Tropical Cyclone Eyewall Ring Evolution - Sawyer-Eliassen Model Diagnosis

Applying a 3-D full-physics model, this study demonstrates that the tropical cyclone eyewall evolves following a very different path as compared with those demonstrated by the dry barotropic model in many previous studies. Provided with enough diabatic heating, a persistent eyewall ring structure can be sustained in WRF simulations with sophisticated physics processes. It is herein of interest to investigate the mechanism maintaining the eyewall ring structure. Potential vorticity budget analyses show that both the diabatic heating term and the advection term have equally important impacts on the eyewall ring evolution, yet their influences offset each other.

To gain more physical insights into this issue, the Sawyer-Eliassen (SE) model is applied to evaluate the impact of different amounts of diabatic heating on the evolution of the eyewall ring. The difference of the SE-model-diagnosed relative vorticity tendency in response to different amounts of diabatic heating shows a ring-like pattern, indicating the important role the convective heating may have played in maintaining the eyewall ring structure. The impact of diabatic heating on the vortex's ring initial structure, as well as the model physics, are being further investigated to provide better pictures and comprehensive understandings of this scientific problem.