Contact: Tom Parisi, NIU Office of Public Affairs
(815) 753-3635 or tparisi@niu.edu

Stephanie Kenitzer, AMS press office
(425) 432-2192 or Kenitzer@dc.ametsoc.org

March 21, 2002

A joint announcement from the American Meteorological Society
and Northern Illinois University

Researchers track Illinois storm damage
to crops via NASA satellite

Researchers say they used data produced by a NASA satellite orbiting more than 400 miles above the earth to estimate the cost of crop damage from hail and wind storms that swept through west-central Illinois, the heart of America's farmlands.

"This could become the preferred method for assessing crop destruction from any natural or man-made disaster," said Mace Bentley, lead author of a study on the satellite assessment technique.

The study is published on the cover of the March Bulletin of the American Meteorological Society. Bentley is a meteorology professor in the Department of Geography at Northern Illinois University.

Bentley said imagery produced from the satellite data found significant damage that went undetected by traditional means of assessment. Bentley and University of Georgia researchers Thomas Mote and Paporn Thebpanya used data produced by the U.S. satellite known as Landsat 7, which acquires high-resolution images of the earth's land surface.

Each year more than 20,000 thunderstorms erupt in the United States, causing between $1 billion to $3 billion in property and agricultural losses. Many of the most damaging thunderstorms with extensive winds and hail are concentrated in the country's central plains and Corn Belt regions and occur during the late spring and summer months, the primary growing season.

"You're definitely going to see Landsat data used more and more often to assess damage not only from thunderstorms but also from tornadoes, brush fires and any other disaster that destroys vegetation," Bentley said.

"Spatial mapping of agricultural damage could be used by farmers, insurance companies and even meteorologists examining storm formation and downburst potential," he added. "Combining this technology with radar would help meteorologists identify and be able to recognize storm features that produce the greatest amounts of damage. As advances in satellite remote sensing continue, there is also evidence that these techniques could prove useful for damage assessment in urban and suburban areas as well. Additionally, storm damage assessment using satellite data gives us global coverage."

Bentley said the satellite-produced imagery has distinct advantages over standard methods of storm-damage assessment, which typically consist of drive-by observations or occasional aerial photography. Those methods are particularly inadequate when trying to estimate the number of acres damaged, Bentley said. "Using data from the Landsat 7 represents a superior method of identifying actual acres that sustain damage," he said.

Landsat 7 data can be used to measure differences in ground reflectance among different land-surface types. The satellite can detect chlorophyll absorption in vegetation and will identify changes in ground reflectance once crops have been destroyed-or within a week to 10 days after a storm, Bentley said. With the launch of Landsat 7 in 1999, the cost of acquiring data has dropped significantly, he added.

The researchers specifically examined two wind and hail storms that rolled through a total of 14 counties in the corn- and soybean-rich region of west-central Illinois on Aug. 12 and Aug. 18 of 1999. The researchers compared data from July 12 (before the storms) and Aug. 28 (after the storms) to determine damage extent.

The major storm on Aug. 12, destroyed thousands of acres of corn across the area, causing more than $53 million in crop damage in eight counties, according to estimates published in Storm Data, a monthly publication produced by the National Climatic Data Center. A second series of storms six days later caused an additional $4 million in hail damage to corn and soybeans.

In comparison, Landsat 7 data detected more than $100 million in damage from the two storms. However, due to prevailing soft-soil conditions and the ability of farmers to modify harvesting equipment to salvage blown-down crops, actual losses were only a fraction of that.

"Conditions were just right to make the crops salvageable, something we couldn't determine from the satellite imagery alone," Bentley said, adding that the case study points to one limitation of using the satellite data.

"It's much easier to determine hail damage than wind damage," he said. "That's not real surprising because large hail pulverizes crops. Wind, on the other hand, may simply blow the crops over. Sometimes portions remain rooted and still survive, though less productive and more difficult to harvest.

"Satellite images sometimes show a different picture than the actual storm reports," Bentley added. "By combining the old-fashioned methods of storm-damage assessment with the high-tech imagery, we can get more accurate readings of crop damage. And when we're talking about millions of dollars in potential losses, that's good news for farmers and insurance companies."

Illinois counties studied in the analysis were Adams, Brown, Cass, Fulton, Hancock, Logan, Mason, McDonough, Menard, Morgan, Pike, Sangamon, Schuyler and Scott.

The American Meteorological Society (http://www.ametsoc.org/ams) is the nation's leading professional society for scientists in the atmospheric and related sciences.

###

Note to Editors:

This release, downloadable photos, a satellite image and charts are available at http://www.niu.edu/pubaffairs/presskits/storm.

PDF or faxed copies of the paper are available to journalists from Stephanie Kenitzer, AMS press office (425-432-2192) or Kenitzer@dc.ametsoc.org.

Researchers' contact information:

• Mace Bentley, Dept. of Geography, Northern Illinois University
  Ph: (815) 753-6850; E-mail: bentley@geog.niu.edu
• Thomas L. Mote, Dept. of Geography, University of Georgia
  Ph: (706) 542-2906; E-mail: tmote@uga.edu