Supercells and Tornado-Like Vortices in an Idealized Global Atmosphere Model

We investigate the representation of individual supercells and intriguing tornado-like vortices in a simplified, locally refined global atmosphere model. The model, featuring grid stretching, can locally enhance the model resolution and reach cloud-resolving scales with modest computational resources. Given a conditionally unstable sheared environment, the model can simulate supercells realistically, with a near-ground vortex and funnel cloud at the center of a rotating updraft reminiscent of a tornado. An analysis of the Eulerian vertical vorticity budget suggests that the updraft core of the supercell tilts horizontal vorticity into the tornado-like vortex, which is then amplified through vertical stretching by the updraft. Results suggest that the simulated vortex is dynamically similar to observed tornadoes, as well as those simulated in modeling studies at much higher horizontal resolution. Lastly, we discuss the prospects for the study of cross-scale interactions involving supercells. We use a simplified global model to study individual supercells and intriguing cloudy rotating winds that behave like tornadoes. This model uses grid-stretching techniques, making it a computationally efficient tool to study supercells on a real-size Earth. Unlike most numerical models of tornadoes which simulate scales of a few tens of meters, our model can realistically simulate supercells and cloudy tornado-like rotating winds even at kilometer scales, which appears unprecedented in the literature. We find that the physics behind the rotating winds is consistent with previous studies, including observations of tornado formation and simulations at much higher resolution. The findings of this study open the door to a better understanding of complex interaction between supercells, tornadoes, and their environment. The FV3 dynamical core with simple microphysics can simulate individual supercells and cloudy tornado-like vortices at kilometer scales A stretched cubed-sphere grid is used to economically reach cloud-resolving scales locally on a real-size Earth The dynamics of the simulated tornado-like vortices is consistent with previous studies on tornadogenesis