Title: Progress in the Simulations of Supercell Tornadoes
Lecturer: Prof. Richard Rotunno (NCAR)
Inviter: Prof. Zhe-Min Tan
Time: Monday November 17, 2025 at 10:00 AM
Venue: Lecture Hall D102, School of Atmospheric Sciences
Abstract: The major advances in the numerical simulation of supercell tornadoes have come through improved numerical-simulation models of supercell convective storms, which contain the tornado's parent circulation. These simulations are carried out on a large domain (to capture the supercell’s circulation system), but with high resolution and improved representations of sub-grid physics (to capture the simulated tornado-like vortex or TLV). The present work analyzes a state-of-the art supercell simulation carried out using the technique of Large Eddy Simulation (LES) including surface friction. To bring the analysis of these supercell-produced TLVs a step closer to observations and theory, the TLV in an advanced supercell simulation is identified as the tornado center, and the Cartesian model velocities are transformed to cylindrical coordinates and azimuthally averaged. A theory for the rotating-flow boundary layer with radial and azimuthal inflow velocities modeled on the axisymmetric analysis is shown to produce good qualitative agreement with the analyzed axisymmetric TLVs.
Brief introduction to the speaker: Richard Rotunno is a Senior Scientist in the MMM Laboratory at NCAR. He received a Ph. D. in 1976 in Geophysical Fluid Dynamics from Princeton University. Rich's research has ranged over a wide variety of topics in mesoscale dynamical meteorology, through a combination of theory and numerical modeling. Rich is a two-time recipient of the AMS Banner I. Miller Award, also the recipient of the AMS Jule G. Charney Award (2004), Carl-Gustaf Rossby Research Medal (2017) and Lifetime Achievement Award (2018). In 2023, he was elected to the U. S. National Academy of Science.