Imported and Storm-Generated Near-Ground Vertical Vorticity in a Simulated Supercell

The authors use a high-resolution supercell simulation to investigate the source of near-ground vertical vorticity by decomposing the vorticity vector into barotropic and nonbarotropic parts. This way, the roles of ambient and storm-generated vorticity can be isolated. A new Lagrangian technique is employed in which material fluid volume elements are tracked to analyze the rearrangement of ambient vortex-line segments. This contribution is interpreted as barotropic vorticity. The storm-generated vorticity is treated as the residual between the known total vorticity and the barotropic vorticity.