Examining the Impact of Rainband Convection on TC Evolution Using Idealized Simulations

The dynamics of the shear-induced stationary rainband complex and its impact on the larger tropical cyclone remain an uncertain area that requires further investigation. The stratiform sector within the stationary rainband complex, in particular, has a large spatial coverage which makes it capable of readily interacting with the vortex-scale wind field and impacting the storm evolution. As found by previous observational and modeling studies, the secondary circulation within the stratiform sector enhances the tangential wind field and broadens the overall storm, possibly contributing to further structural and intensity changes associated with eyewall replacement cycles. In this study, we further investigate the impact of the stratiform rainband on tropical cyclone evolution using a series of idealized WRF-ARW model simulations. Specifically, we examine the vortex dynamic response to artificial heat sources representative of this rainband convection. Here, we extend the work of previous studies that have performed similar idealized investigations by designing heating structures that are more closely aligned with detailed rainband observations.
A dry vortex configuration, in which all physical parametrizations are turned off, is used to separate the impact of the imposed heating from that of the different parametrization schemes. The performance of this dry model is first validated using the Eliassen balanced vortex model under the axisymmetric framework. Next, a realistic spiral heating structure representative of the stratiform rainband is superimposed on an idealized vortex circulation. We examine the kinematic and thermodynamic response of the vortex and assess the overall impact on the TC evolution. We perform sensitivity tests by perturbing the heating structures, the initial vortex, and the surrounding environment. Our results provide further insight to the role of the rainband complex in structural and intensity changes of TCs.