Kellner said these "rings" of increased tornado activity could be related to how cities are developed.
"Cities impact the surrounding climate in terms of regional airflow and temperature," she said. "The size of cities, what they're made of and the heat they produce are factors that could affect the microclimate."
Niyogi cautioned that every storm is unique and that a variety of factors influence storm intensity and the potential for severe weather. Identifying areas of high risk, however, could lead to city designs that would reduce the conditions associated with producing severe weather hazards such as tornadoes.
"As we continue to modify our landscapes, there will be many environmental and societal changes," he said. "But perhaps we have the potential to engineer cities to be more resilient to severe weather by thinking holistically about the way cities can be developed and how they affect local climate conditions."
According to the study, Indiana has a distinct spring tornado season with a majority of tornadoes occurring in June, May and July, respectively. Strong tornadoes with estimated wind speeds of more than 158 miles per hour occur most frequently in April and June. The total number of tornado days per year - days on which at least one tornado report is made - has not increased over time.
The study also found that drought conditions and climate variations such as El Niño have some impact on Indiana tornado climatology.
The paper was published in the American Meteorological Society's Earth Interactions journal and is available at http://journals.ametsoc.org/doi/abs/10.1175/2013EI000548.1
Funding for the research was provided in part by a NASA Fellowship Grant awarded to Kellner, the National Science Foundation's STRONG Cities Project and the U.S. Department of Agriculture's National Institute of Food and Agriculture.