Satellite data used to show how much moisture plants give off to predict dry conditions.
Weather researchers are developing a new tool they say could give Oklahoma farmers and ranchers as much as a month’s warning when drought conditions are on the way.
The Evaporative Stress Index http://hrsl.arsusda.gov/drought/ is a system being developed by the United States Department of Agriculture that uses satellite data to predict drought. An experimental version of the index is online now, and researchers expect the full version will be available next year.
Jason Otkin, an assistant scientist in the University of Wisconsin’s Cooperative Institute for Meteorological Satellite Studies, said the system uses data that show how much moisture plants give off into the atmosphere to predict dry conditions.
As plants draw water from the soil, they release water vapor into the atmosphere through small pores on the underside of leaves, a process called transpiration. Otkin, a member of the team developing the system, said when water becomes scarce and plants are stressed, they give off less water vapor.