A Statistical Analysis of Surface Roughness Influences on Tornadogenesis and Tornado Decay within the Southeastern United States
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Date
2023-05
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The Ohio State University
Abstract
As tornadic activity increases in the Southeastern United States (Agee et al. 2016), it becomes imperative to investigate tornadic activity in this region. Given that patterns of land cover greatly differ between the Southeast and the traditional Tornado Alley and that surface roughness has been well documented to affect the structure and behavior of tornadoes (Bode et al. 1975; Dessens 1972; Kuai et al. 2008; Matsui and Tamura 2009; Natarajan and Hangan 2009, 2012; Neakrase and Greeley 2010; Wang et al. 2017; Zhang and Sarkar 2008), investigating the relationship between surface roughness and tornadic activity in the Southern U.S. would be a worthwhile enterprise. A hotspot analysis of tornadogenesis and tornado decay points, was performed within four states within the region with high tornadic activity (Alabama, Georgia, Mississippi, and Tennessee). Additionally, statistical comparisons of the frequency of tornadogenesis and decay within each of the categories of land cover as defined by the National Land Cover Database (NLCD) were made in each of the four states of study. Finally, the average surface roughness length in the immediate areas surrounding the tornadogenesis and decay points were statistically compared to the surface roughness lengths in the surrounding environments. Results indicated that tornadoes were more likely to form and dissipate in developed areas and at sites in which the average surface roughness greatly differed from the average surface roughness in the immediate environment. While some studies (Cusack 2014) have indicated the potential that urban environments are more likely to produce tornadogenesis, it is impossible to come to a firm conclusion of causation given the possibility of damage indicator reporting bias when it comes to tornado tracks and spatial correlation bias when it comes to land cover analysis.