In the bowels of a devastating tornado thanks to this simulation

Using a powerful supercomputer, meteorologists successfully simulated the devastating Category 5 “El Reno” tornado that swept through Oklahoma, USA in May 2011 .

At the University of Wisconsin-Madison’s Cooperative Institute for Meteorological Satellite Studies (CIMSS), a research team led by Leigh Orf used a high-efficiency supercomputer to visualize the internal mechanism of tornadoes, as well as the powerful supercells that cause them. the origin. As part of this project, they successfully simulated the supercells that produced the tornado that devastated the Great Plains region of southern Oklahoma in 2011. These new models offer new insights into these monstrous storms and on how they are formed.

This work is relevant, the United States being in the lead of the countries most affected by this phenomenon with more than 1200 tornadoes that affect the country each year according to the National Oceanic and Atmospheric Administration (NOAA).

Over approximately four days in late May 2011, several tornadoes touched down in Oklahoma. One of them, called « El Reno », was classified as category 5 on the improved Fujita scale, the maximum, causing extensive damage and costing the lives of nine people for 161 injured.

To simulate the incredibly complex set of weather factors needed to produce a tornado of this power, Leigh Orf’s team had access to the Blue Waters supercomputer located at the University of Illinois. Meteorologists used real-world observational data to recreate conditions at the time of the storm, including a vertical profile of temperature, atmospheric pressure, wind speed and humidity. Together, these ingredients contribute to “tornado genesis,” the conditions required for a supercell to become a tornado.

During the simulation, the researchers observed numerous « mini tornadoes » that formed before the main tornado. Then, as the main funnel cloud formed, the smaller tornadoes began to coalesce, adding strength to the superstructure and increasing wind speed.

Eventually, a new structure known as the « streamwise vorticity current » (SVC) formed inside the tornado.  » The SVC is made up of cooled rain air that is drawn into the updraft that drives the entire system “Explains Leigh Orf in a press release from the University of Wisconsin.  » We think this is a crucial element in sustaining an unusually strong tornado, but what’s interesting is that the SVC is never in contact with the tornado. “, he adds.

 » We have finished this simulation, but we are not going to stop there. We will continue to refine the model and continue to analyze the results to better understand these dangerous and powerful systems. “, concludes the meteorologist.


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