DECIPHERING SOIL MOISTURE AND SURFACE COMPOSITION OF THE WORLD'S DRYLANDS USING THERMAL INFRARED AIRBORNE AND SPACEBORNE DATA

With continuing climate change, most of the Earth’s drylands will experience increasing temperatures and decreasing precipitation. Expanded and persistently intense droughts, increased soil erosion, more intense fires and reduced soil moisture can all be expected. Such changes in the southwestern United States for example could greatly affect the general habitability and agricultural productivity of these areas. Synoptic measurements of these surface processes are becoming increasingly important as a marker of drought and input variables into land-atmosphere feedback models. New thermal infrared (TIR) and visible/short wave infrared (VSWIR) data acquired from the air, from orbit as well as from the ground are providing a unique tool to detect soil moisture. Studies have been conducted at two locations in the southwestern US (an agricultural site and a natural eolian system) and are able to detect small changes in soil moisture over time. The accuracy of this approach increases with knowledge of surface temperature and composition, which can both be extracted from the TIR data. In a related project, a new airborne instrument called the Mineral and Gas Identified (MAGI) funded by the NASA Instrument Incubator Program was built and flown by the Aerospace Corporation. The instrument is testing possible new technologies for the future NASA HyspIRI mission. MAGI data of the Salton Sea region in California are being used to both refine the proposed spectral bandpass positions of HyspIRI and better understand the thermal and compositional variability of this geothermal region. Combined, these studies show that future HyspIRI TIR data have the potential of providing innovative and integrated synoptic measurements of surface composition, soil moisture and geothermal activity at other semi-arid sites around the globe; and will be important for monitoring the effects of climate change on the surface.