Statistical and Empirical Relationships between Tornado Intensity and Both Topography and Land Cover Using Rapid-Scan Radar Observations and a GIS

Abstract

This study presents an investigation into relationships among topographic elevation, surface land cover, and tornado intensity using rapid-scan, mobile Doppler radar observations of four tornadoes from the U.S. Central Plains. High spatiotemporal resolution observations of tornadic vortex signatures from the radar’s lowest elevation angle data (in most cases ranging from ~100-350 m above ground level) are coupled with digital elevation model (DEM) and 2011 National Land Cover Database (NLCD) data using a Geographic Information System (GIS). The relationships between 1) tornado intensity and topographic elevation or surface roughness and 2) changes in tornado intensity and changes in topographic elevation or surface roughness are investigated qualitatively, and statistical relationships are quantified and analyzed using a bootstrap permutation method for individual case studies and all data collectively. Results suggest that there are statistically significant relationships for individual cases, but the relationships defy generalization and are different on a case-by-case basis, which may imply that they are coincidental, indicating a null correlation.

Predicting Risks of Severe Windstorm Damage to Southeastern U.S. forests

“…While most tornados in this region have a general southwest to northeast direction (Thom 1963), aspect was also not an important factor in predicting tree damage. Other studies have noted variability between these factors and storm intensity based on location and storm characteristics (Frazier et al 2019;Houser et al 2020). It is possible that the slope/aspect relationship deserves more focused attention in localized risk assessments, and a broad regional approach such as our study may be insu cient for elucidating a clear relationship between those variables and damage risk.…”

“…Surface topography affects tornado direction and intensity, with even small changes in uencing near-surface in ow, structure, and path (Lewellen 2012). Steeper slopes have been shown to increase probability of tornado occurrence, likely due to the role of slope in the creation of updraft, although the relationship between elevation and tornadic activity can vary by region and storm characteristics (Frazier et al 2019;Houser et al 2020). Remote sensing studies after tornado damage in Georgia and Tennessee forests found more severe damage as tornados descended ridges and diminished damage on the ascent, and this pattern was more pronounced on shallower than steeper slopes (Cannon et al 2016).…”

Idealized Simulations of a Supercell Interacting with an Urban Area

“…In addition to gradients in atmospheric properties, supercells have also been found to be influenced by variability in land surface characteristics, particularly terrain [14][15][16][17]. Some studies have also noted that tornado development in supercells may be impacted by elevation changes [18][19][20][21][22] while others have explored the link between tornado formation and variations in surface roughness [22][23][24]. Numerical simulations have also shown that the development of near-ground rotation is sensitive to surface friction magnitude [25][26][27].…”