SSEC scientist leads field in hyper-realistic storm simulation

September 28, 2015 | Sarah Witman

A hyper-realistic storm simulation released by Space Science and Engineering Center (SSEC) scientist Leigh Orf recently won a people’s choice award from XSEDE15, an annual gathering of computing experts.

The simulation is a digital replica of a long-track EF5 storm, the rarest but most devastating type of tornado. Just how realistic is it? See for yourself.

As a researcher at Central Michigan University, Orf spent the past year-and-a-half creating the simulation on the Blue Waters supercomputer at the University of Illinois.

Using data provided by Lou Wicker at NOAA’s National Severe Storms Laboratory, he forecast variables such as wind, temperature, pressure, precipitation, and turbulent kinetic energy with the CM1 open-source atmospheric model, developed at the National Center for Atmospheric Research (NCAR).

He then turned his model data over to visualization specialists Rob Sisneros and David Bock at the National Center for Supercomputing Applications (NCSA), who brought the simulation to life with advanced rendering software.

“Probably no one would mistake it for a real video, but this is the best photorealistic rendering of a supercell I have ever seen,” said Orf, who has studied supercells — storms characterized by powerfully rotating winds — and storm simulation techniques for more than a decade. “It’s breathtaking.”

While visualizations like this are undeniably eye-pleasing, Orf sees them foremost as an important science tool, allowing scientists to validate their modeling with observations.

“We are visual beings; we look with our eyes,” he said. “My philosophy has always been that if you are going to model something, like a thunderstorm, if you can’t visualize it in a way that looks real then there’s probably something wrong with your simulation.”

The finished product represents a real-life storm that occurred near El Reno, OK, and eventually formed a long-track EF5 tornado, on 24 May 2011. Cutting a path one mile wide and 63 miles long, the tornado killed nine people and injured 181 others.

It is the strongest, longest-lasting supercell ever simulated in a cloud model.

Orf said he hopes this breakthrough will lead to answers about what causes these select few tornadoes to persist for up to several hours after forming.

“With everything swirling around, you can’t just look at weather maps,” he said. “These simulations break down the physics taking place inside a storm, to tell you what’s going on.”

Having earned his PhD at the University of Wisconsin-Madison Department of Atmospheric and Oceanic Sciences in 1997, Orf returns to SSEC this fall to continue to pursue his unique brand of supercell simulation.

“I am looking forward to being 100 percent research at SSEC, to devoting all my time to this work,” he said.

“SSEC has a strong set of observational and remote-sensing research groups, and there are a lot of great scientists there that I hope to collaborate with, and branch out,” he added, noting that the upcoming launch of next-generation geostationary satellite GOES-R will improve capabilities to study supercells in far greater detail from space.

Orf said his first goal is to publish the El Reno tornado simulation, and reproduce the results at higher resolutions. He also plans to pick one or more high-profile storms — such as Joplin, MO; Moore, OK; or Tuscaloosa, AL — to use as case studies.

“I see this as the start,” he said. “I want to apply this approach towards similar devastating supercell events, and continue to push the field forward.”

by Sarah Witman