Ottawa’s event is the rare opportunity to study the fallout of dangerous winds without the complicating factor of damage from falling or uprooted trees
By Heather Rivers
Deep in the heart of Ontario’s Tornado Alley, London scientists are using the world’s largest tornado simulator to get a better grip on the damage left by a devastating cluster of twisters that struck the national capital region last fall.
The project is breaking new ground for the researchers at Western University since it’s the first time they’ll look at a tornado’s effects on multiple buildings in a neighbourhood block. And given what scientists are noticing about twisters, their findings could be especially timely in an era of severe weather.
“There have been studies that have shown the well-known Tornado Alley (in the United States) that stretches from Texas to the Dakotas, has been moving east, which means we might see more and more tornadoes in Canada,” said Jubayer Chowdhury, a research scientist and adjunct research professor at Western’s engineering school.
Six tornadoes hit the Ottawa-Gatineau area last September, levelling homes and displacing hundreds of people in communities along both sides of the Ontario-Quebec boundary.
The estimated loss ran to US$300 million, “and that is probably just insured losses,” said Djordje Rominic, another researcher on the Western twister team. “We hope to contribute to mitigating loss that will, for sure, happen.”
Ontario, especially the southwest, is no stranger to tornadoes: A wide zone of the province, from Windsor to Eastern Ontario, is prone to the violent rotating winds. In 2011, Goderich’s town square was torn apart by a tornado that also killed a worker at the world’s largest salt mine nearby.
What’s drawn the interest of the researchers at Western’s WindEEE Dome about the Ottawa tornado cluster is the rare opportunity to study the fallout of those dangerous winds without the complicating factor of damage from falling or uprooted trees.
The scientists, still in the planning stage of their research, are zeroing in on the strongest of the tornadoes that struck the Ottawa area, the one that hit the community of Dunrobin where there were few mature trees. It was the strongest tornado to hit Eastern Ontario since 1902.
The Western team chose the Dunrobin twister because it was both serious in intensity and struck a residential area, said Chowdhury.
“It gives us a better chance to relate the wind to the damage to the houses,” he said.
On the six-level Enhanced Fujita scale, which rates tornado intensity by the damage they cause, from EF0 to EF5, the tornado was an EF3, with wind speeds of 218 to 266 kilometres an hour. The scale runs as high as tornadoes packing winds up to 320 km/h.
Funded by a $110,000 grant from the Institute for Catastrophic Loss Reduction and Mitacs, a not-for-profit research organization, the Western team will simulate the tornado in their wind dome to study its effects on some homes in a scale-model block of 22 houses in Dunrobin.
“We’re trying to mitigate the tornado (damage) risk, so we are trying to better estimate losses from experimental simulations,” said Chowdhury.
It’s potentially life-saving research that could benefit insurance companies, builders and homeowners. It could be used to strengthen building codes, or standards for construction, so that structures can withstand tornadoes better.
“In terms of the loads on the buildings, there isn’t much in the building codes. We’re trying to work toward that,” Chowdhury said.
Canada experiences about 100 tornadoes a year, the researchers say. Scientists have reported a rise in tornadoes in recent years, especially events with multiple twisters.
WindEEE’s past research has focused mainly on damage to isolated buildings from EF1 and EF2 tornadoes, making the latest project new turf.
“This is the first time we are going to investigate the tornado load on multiple buildings in a neighbourhood block setting,” Chowdhury said. “When you know the maximum load the building can experience, then you can design a building to withstand those loads.”
A hexagonal wind dome at Western University, the world’s largest tornado simulator, its name stands for Wind Engineering, Energy and Environment. It measures about 25 metres across.
How does it work?
Six giant ceiling fans and calibrated fans along its perimeter and louvres create different vortex sizes. It can simulate tornados from EF0 to EF3.
U.S. research shows that weather situations with more than one tornado, known as tornado outbreaks, are increasing. But there’s no scientific research to support climate change as the culprit. Scientists say the general trend is toward weaker tornadoes.