Satellites Help USDA Forecast Crop Production

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<b>NASA SATELLITES ALLOW USDA TO SEE WORLD'S LAKES RISE AND FALL</b><br /><br />CLICK FOR PICS<br /><br />A few NASA satellites designed to study heights of Earth's ocean surfaces are now also coming in handy for tracking water levels of inland lakes and reservoirs.<br /><br />When analysts at the United States Department of Agriculture (USDA) Foreign Agriculture Service (FAS) learned that NASA satellites could be used for measuring lake water heights, they saw a chance to get vital information for managing irrigation and forecasting crop production in out-of-the way places.<br /><br />Since early this year, NASA has supplied the USDA with near-real time data on lake and reservoir heights from around the world. The USDA has posted this information on a web site that allows users with a computer and Internet to access it for their varied uses. Analysts who forecast crop production, scientists, in-country water and irrigation managers, those involved in fishing industries, and the general public have all been making use of the site. <br /><br />NASA and the French space agency Le Centre National d’Etudes Spatiales (CNES) teamed up to design, build and launch the TOPEX/Poseidon and the Jason-1 satellites. These satellites were designed to study many aspects of the ocean. The TOPEX/Poseidon satellite, for example, orbits at a height of 1336 kilometers (830 miles) above Earth, and can measure the height of the ocean surface directly underneath the satellite with an accuracy of 4-5 centimeters (better than 2 inches). Jason-1 and TOPEX/Poseidon cover the global oceans every 10 days. With these capabilities, this technology is surprisingly valuable for looking at larger areas of inland water.<br /><br />"The satellites were designed with oceanographic objectives in mind, so the fact that they can be used for lakes and rivers are an added bonus," said Charon Birkett, a University of Maryland researche