The dynamic response of the hurricane wind field to rainband heating. Part I: The model and basic results

One of the primary goals of the RAINEX field project was to determine the effects, if any, of spiral rainbands on hurricane intensity and structure. We present a new method for simulating, visualizing, and understanding the impact of diabatic heating in rainband convection on the surrounding flow. This method uses the linear but fully nonhydrostatic model of vortex dynamics developed by the first author and his collaborators that is now knows as 3DVPAS. Diabatic heat sources with three-dimensional structures that are modeled after observed spiral bands are embedded in the circulation of a balanced, baroclinic, hurricane-like vortex. The model simulates the time-evolving symmetric and asymmetric responses to the diabatic heating. Convective, stratiform, and mixed convective-stratiform heating profiles can be used. Well-known features of the wind field around spiral bands are recovered, such as the increased low-level inflow into the band, sinking motion inside the band, and a jet of accelerated flow along the outside of the band.

In Part II, more details of the results will be presented, along with comparisons to RAINEX observations and high resolution simulations.