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Studying Soil Moisture via Remote Sensing

Through evaporation and plant transpiration, soil moisture is an important factor in the exchange of water and heat energy between the land and the atmosphere. In turn, this affects weather patterns and precipitation. Dr. Charles "Chip" Laymon, a hydrologist and remote sensing scientist at USRA's Science and Technology Institute, has worked with scientists and engineers to develop microwave instruments for use in space missions to collect remote sensing data. Ultimately, he and his collaborators will create new algorithms to more precisely estimate soil moisture in the top 10 centimeters of the ground. Dr. Laymon conveys the importance of collecting this data: "...consequences of climate change are realized in the water cycle - water in the environment, water supply and quality, water for consumption." In 2007, the NRC Decadal Survey recommended the Soil Moisture Active Passive (SMAP) as a first phase mission (2010-2013), and in February 2008, NASA selected the mission and determined its first launch window (2012).

Two instruments Dr. Laymon has worked on are the MAPIR and the OMEGA instruments. MAPIR (Marshall Airborne Polarimetric Imaging Radiometer), which was first flown in 2008, flies onboard NASA aircraft and observes radiation that is naturally emitted from the ground. This radiometer uses remote sensing to retrieve information on soil moisture, surface or water temperature, and ocean salinity. MAPIR is a dual beam, dual angle polarimetric scanning L-band passive microwave radiometer system developed by the OMEGA team at Marshall Space Flight Center (MSFC). Dr. Laymon also assisted with OMEGA (Observing Microwave Emissions for Geophysical Applications) instruments that capture soil moisture data, which improve weather models; [in turn], better weather models result in better weather forecasts. Says Laymon, "The ultimate goal is a three-tiered data collection: OMEGA instruments on a truck and onboard a plane as well as a similar instrument, built by NASA's JPL, on a satellite." The soil moisture data from each sensor will then be retrieved and analyzed.

Such studies of soil moisture are beneficial to societies in general and to farmers specifically: by improving forecast models, meteorologists and scientists are better prepared to predict droughts, landslides and floods, and farmers can better determine irrigation plans and crop yields.