Identifying Severe Thunderstorm Wind and Tornado Damage Utilizing Synthetic Aperture Radar

A rapid damage assessment after severe weather events, especially when tornadoes are suspected, is crucial for supporting response and recovery activities. The impacts caused by these events can cover a large area over varying land cover and terrain. Traditional ground surveys can be especially challenging in rural areas with poor road networks or inaccessible, densely vegetated areas, making documentation difficult. Optical remote sensing data has successfully assisted with damage surveys in these inaccessible areas. In recent years, high-resolution commercial and drone imagery have also been used. Though beneficial, optical sensors are impacted by solar illumination and clouds, limiting when they can be used. In contrast, synthetic aperture radar (SAR) is an active sensor that allows usable collections regardless of most atmospheric conditions. The main objective of this presentation is to leverage observations from multiple SAR wavelengths to determine their feasibility in detecting damage after severe weather events, especially those with damaging winds and tornadoes. Two severe thunderstorm outbreaks from the winter and early spring across the Southeast in 2023 were evaluated. SAR data from three sensors of varying wavelengths were analyzed: ESA’s Sentinel-1 C-band, JAXA’s ALOS-2 L-band, and a high-resolution commercial X-band sensor, ICEYE. A combination of SAR backscatter and interferometric synthetic aperture radar (InSAR) products (i.e., coherence) were analyzed first to identify visible tornado tracks. Physical characteristics (i.e., length and width) from tornado tracks that could be identified were then compared to the official damage surveys. Additional change detection products using SAR imagery will be presented and compared to optical imagery to showcase the strengths and limitations of varying wavelength SAR acquisitions for severe weather damage identification. SAR could be a beneficial supplementary dataset to optical data and ground surveys, especially when surveying difficult terrain and hard-to-reach areas.