Simulation of Near-surface Mesocyclogenesis during Mergers between Mature and Nascent Supercells

Prior simulations of mergers between mature and nascent supercells show that during or following certain types of mergers, an intensification in the near-surface vorticity field occurs. This intensification is similar to certain real-world mergers. In order to investigate this further, trajectory and circulation analyses of the simulated mergers are employed to find the reasons for the rapid intensification of low-level vorticity. For rear-flank mergers, the distribution of precipitation during the merger enhances the baroclinic vorticity generation along the trajectories bound for the low-level mesocyclone, but without producing an excessively cold outflow.