A tornado track is a path of devastation on the ground as seen from space, and scientists are using satellite images to determine tornado tracks that were not visible to the human eye.
( Image: A tornado left this track when it ripped through Tuscaloosa, Ala., on April 27, 2011. But not all twisters leave such unambiguous scars. GOOGLE EARTH, GEOEYE)
The analysis could help researchers study storms that strike in the winter
By Katherine Kornei, Science News , APRIL 9, 2023 AT 7:00 AM
When a strong tornado roars through a city, it often leaves behind demolished buildings, broken tree limbs and trails of debris. But a similarly powerful storm touching down over barren, unvegetated land is much harder to spot in the rearview mirror.
Now, satellite imagery has revealed a 60-kilometer-long track of moist earth in Arkansas that was invisible to human eyes. The feature was presumably excavated by a tornado when it stripped away the uppermost layer of the soil, researchers report in the March 28 Geophysical Research Letters. This method of looking for “hidden” tornado tracks is particularly valuable for better understanding storms that strike in the winter, when there’s less vegetation, the researchers suggest. And recent research has shown that wintertime storms are likely to increase in intensity as the climate warms (SN: 12/16/21).
Jingyu Wang, a physical geographer at Nanyang Technological University in Singapore, and his colleagues set out to detect the signatures of those deadly storms in unpopulated, barren landscapes.
Swirling winds, even relatively weak ones, can suction up several centimeters of soil. And since deeper layers of the ground tend to be wetter, a tornado ought to leave behind a telltale signature: a long swath of moister-than-usual soil. Two properties linked with soil moisture level — its texture and temperature — in turn impact how much near-infrared light the soil reflects.
Wang and his collaborators analyzed near-infrared data collected by NASA’s Terra and Aqua satellites and looked for changes in soil moisture consistent with a passing tornado.
When the team looked at data obtained shortly after the 2021 storm outbreak, they noticed a signal in northeastern Arkansas. The feature was consistent with a roughly 60-kilometer-long track of wet soil. Tornadoes had been previously reported in that area — outside the city of Osceola — so it’s likely that this feature was created by a powerful storm, the team concluded.
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