Soil Moisture Observations From Shortwave Infrared Channels Reveal Tornado Tracks: A Case in 10–11 December 2021 Tornado Outbreak

• Published in: Geophysical research letters Vol. 50; no. 6
• Main Authors: Wang, Jingyu, Lin, Yun, McFarquhar, Greg M., Park, Edward, Gu, Yu, Su, Qiong, Fu, Rong, Lee, Kee Wei, Zhang, Tianhao
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28-03-2023; Wiley
• Subjects: Agricultural land; Channels; Clay; clay content; Clay soils; Damage detection; Detection; Imaging techniques; Infrared tracking; Latency; MODIS; Moisture content; Moisture effects; Outbreaks; Plant cover; Resolution; Scars; Short wave radiation; shortwave infrared; Soil; Soil layers; Soil moisture; Soil structure; Soil types; Soils; Spatial discrimination; Spatial resolution; Spectroradiometers; Tornado damage; tornado track; Tornado tracks; Tornadoes; Vegetation; Vegetation changes; Vertisols; Water content; Winter; United States > US; Arkansas
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL102984

Satellite‐based post‐tornado assessments have been widely used for the detection of tornado tracks, which heavily relies on the identification of vegetation changes through observations at visible and near‐infrared channels. During the deadly 10–11 December 2021 tornado outbreak, a series of violent tornadoes first touched down over northeastern Arkansas, an area dominated by cropland with rare vegetation coverage in winter. Through the examination of Moderate Resolution Imaging Spectroradiometer multi‐spectral observations, this study reveals significant scars on shortwave infrared channels over this region, but none are captured by visible and near‐infrared channels. The dominant soil type is aquert (one of vertisols), whose high clay content well preserves the severe changes in soil structure during the tornado passage, when the topmost soil layer was removed and underlying soil with higher moisture content was exposed to the air. This study suggests a quick post‐tornado assessment method over less vegetated area by using shortwave infrared channels.
Plain Language Summary
This study showcases an application of using Moderate Resolution Imaging Spectroradiometer (MODIS) data to detect tornado damage tracks over northeastern Arkansas after the deadly 10–11 December 2021 tornado outbreak. The special soil type with rich clay content well retains the tornado scars, whose moisture content is higher than the surrounding area, causing significant signals on MODIS shortwave infrared channels. Although coarse in spatial resolution, MODIS’s rapid revisit cycle and minimal latency in data availability make it an ideal platform for the post‐tornado assessment over the winter farmland, when the vegetation coverage is low, thus the conventional vegetation‐based tornado track detection does not work well.
Key Points
The 2021 winter tornado outbreak left significant linear scars on Arkansas aquert farmland observed from Moderate Resolution Imaging Spectroradiometer (MODIS) shortwave infrared (SWIR) channels
The scars are unrecognizable on MODIS visible and near‐infrared channels due to the coarse resolution and rare vegetation cover in winter
SWIR provides a fast assessment of tornado track as topmost layer is removed by suction vortices and wetter underlying soil is exposed