Chuck Bednar for redOrbit.com – Your Universe Online
Wildfires and forest fires can have an unexpected on the weather, as smoke from those events can actually increase the intensity of tornadoes, researchers from the University of Iowa report in the latest edition of the journal Geophysical Research Letters.
In the study, UI chemical and biochemical engineering professor Gregory Carmichael, Center for Global and Regional Environmental Research (CGRER) postdoctoral fellow Pablo Saide, and their colleagues examined the impact of smoke from land-clearing spring agricultural fires in Central America on a severe weather outbreak that occurred in 2011.
That outbreak, which took place on April 27, produced a total of 122 tornadoes and resulted in 313 deaths across the southeastern US. It is believed to be the most severe event of its kind since 1950, and the researchers found that smoke from those Central American fires played a role.
Shear luck
According to the study authors, the outbreak was caused primarily by supercell-producing environmental conditions. But the smoke particles intensified those conditions, Saide and Carmichael noted.
The duo reported the smoke caused the base of the clouds to lower and increased wind shear, which is the variation of wind speed in respect to altitude. Combined, those factors increased the likelihood of more severe tornadoes. It marks the first time that the impact of smoke has been linked to this phenomenon, and the research has found the reasons for these interactions.
“These results are of great importance, as it is the first study to show smoke influence on tornado severity in a real case scenario,” Carmichael explained in a statement. “Also, severe weather prediction centers do not include atmospheric particles and their effects in their models, and we show that they should at least consider it.”
“We show the smoke influence for one tornado outbreak, so in the future we will analyze smoke effects for other outbreaks on the record to see if similar impacts are found and under which conditions they occur,” added Saide. “We also plan to work along with model developers and institutions in charge of forecasting to move forward in the implementation, testing and incorporation of these effects on operational weather prediction models.”
Their findings are based on computer simulations based on data collected during that 2011 event. In one of those models, smoke and its effect on solar radiation and clouds were included, while the other omitted smoke. The simulation which included the smoke resulted in a lowered cloud based and greater wind shear.
Carmichael, who also serves as director of the Iowa Informatics Initiative and co-director of CGRER, added that future research on the field will focus on improving scientists’ understanding of how smoke can impact near-storm environments and tornado occurrence, intensity, and longevity.
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