Satellite images tell tale of Siren tornado

The morning after the northwestern Wisconsin town of Siren was leveled by a devastating tornado, the federal Landsat-7 satellite captured its destructive path from space.

The orbit of the satellite, which makes a 16-day pass of the globe, just happened to coincide with the morning after the June 18 storm. That set the stage for researchers at the Environmental Remote Sensing Center to construct a high-resolution before-and-after documentation of the storm’s damage.

“Timing is everything when trying to document these events via satellite,” says Thomas Lillesand, director of the remote sensing center, part of the Institute for Environmental Studies. “We were fortunate to have cloud-free images of the area collected both the day after the tornado and essentially one month earlier. We could then register the two images and highlight the damaged areas using digital image processing techniques.”

Lillesand and his fellow researchers have extensive experience in processing satellite data for a range of environmental monitoring and natural resource management applications. For example, Landsat data are being used to measure the transparency of Wisconsin’s more than 15,000 lakes.

This cooperative effort is being conducted jointly with the Wisconsin Department of Natural Resources and the hundreds of citizen volunteers who participate in the DNR Self-Help lake monitoring program. UW–Madison’s ongoing water quality research is known as the Satellite Lake Observatory Initiative.