A compressible, non-hydrostatic model is used to investigate atmospheric circulations induced by annular surface heat sources in a vertically sheared crossflow. Annular heat sources are used to approximate the influence of a wildland fire on the atmospheric flow. A series of simulations with varying heat source radii are used to derive a relationship between heat source diameter, intensity and changes in vertical vorticity relative to the point source (zero radius) case.

Plumes above an intense point source in a crossflow tend to bifurcate as a pair of counter-rotating vortices develops above the heat source. These vortices are commonly observed in smoke plumes from wildland fires, but wildland fires are not point sources. This study seeks to determine at what spatial scales/intensities does the heat source support the development and maintenance of this vortex pair.