Streamwise Vorticity in a Supercell Thunderstorm

Science Behind the Image

This wild-looking image compares variables from the dataset of a simulated hypothetical thunderstorm that spawned a tornado. The plot shows vortex lines, the gold streamlines modeled from vorticity, compared with wind velocity as grey streamlines with red representing highest speed values. The scene illustrates rotation in the updraft, the hallmark characteristic of a supercell. Featured is a vortex ring at the top of the storm, which forms as the strong updraft punches into the stable stratosphere and the air subsequently curls downward. A translucent volume rendering of cloud water combined with ice provides reference to the surrounding storm structure. In a real storm, you can see the clouds billowing upward and corkscrew striations in the rotating cloud, but the relationship between the wind and rotation isn't exactly clear. Plots like this help to illuminate this relationship giving a better sense of how the vorticity in the environment is tilted, stretched, and intensified in the updraft to make the storm rotate. The image illustrates how vorticity in the environment aligns with the winds feeding into the storm to enhance storm rotation.

Visualization Behind the Image

The visualization illustrates a structure in the dataset that the researcher wasn't aware of — the vortex ring. The meteorologist plans to incorporate this image in an upcoming seminar, and TACC will use the image in venues to promote the NSF XSEDE initiative, HPC, and visualization resources. The visualization was created with VisIt software (Lawrence Livermore National Lab) on Longhorn at the Texas Advanced Computing Center. The simulation was run on Kraken (National Institute for Computational Sciences). More specifically, TACC staff had to translate the netcdf data from the simulation into hdf to incorporate the irregular spaced Z coordinates that the user provided. The 1500x1500x50 grid is regular in x & y and the dataset includes several variables including wind velocity, reflectivity, perturbated potential temperature, cloud water mixing ratio, ice, vorticity, and others. TACC staff built several animations and stills.



Greg Foss
Greg Abram

University of Oklahoma

Brittany Dah
Amy McGovern