Mahta Moghaddam is a professor in the USC Viterbi School of Engineering’s Ming Hsieh Department of Electrical Engineering, and director of the Microwave Systems, Sensors and Imaging Lab at USC (MiXIL). Her research interests include radar systems, microwave remote sensing for environmental applications, medical imaging, and focused microwave therapy.
Moghaddam uses HPCC resources in her capacity as principal investigator of the Airborne Microwave Observatory of Subcanopy and Subsurface (AirMOSS) project, a mission of the National Aeronautics and Space Administration (NASA) that studies how dynamics and heterogeneities of root zone soil moisture (RZSM) control ecosystem carbon fluxes in North America.
Moghaddam’s team employs a P-band (70 centimeter wavelength) radar instrument—designed and constructed by the Jet Propulsion Laboratory (JPL) and attached to a Gulfstream-III aircraft operated by NASA’s Johnson Space Center (JSC) — to measure scattering cross sections in order to compute the RZSM of vegetation in forest and grassland ecosystems. This information is used in hydrologic and ecosystem process models to determine how much carbon these ecosystems are sequestering and releasing, depending on the available water at their roots. The difference, also called the Net Ecosystem Exchange (NEE) of carbon into the atmosphere, is essential for a better understanding of global climate change.
Using P-band wavelengths, the radar penetrates vegetation canopies and soil to determine how much water lies in the root zone. Measurements are being taken many times as the aircraft flies repeatedly over ten sites in North America over a period of 3 years. Each flyover generates half a million pixels of high-resolution digital imagery, with each pixel representing an area of 30 to 100 meters squared. For analysis, these measurements are run through nonlinear optimizations, using parallel processing on the team’s dedicated cluster, providing the first temporally and spatially sustained direct observations of RZSM. Moghaddam’s work represents the first time such information has been collected and provided to scientists on a large scale.
AirMOSS, led by Moghaddam, is a $25.8M project supported by NASA. Thismultidisciplinary collaboration includes USC, JPL, JSC, the Massachusetts Institute of Technology, Harvard University, Purdue University, Oregon State University, NASA Goddard Space Flight Center, U.S. Department of Agriculture, and U.S. Geological Survey. Moghaddam’s team is also engaged in a number of other projects sponsored by NASA, the National Science Foundation, and the U. S. Department of Defense.
ABOVE: High-resolution P-band radar image—taken in Walnut Gulch, Arizona—of subsurface soil water content, which shows the soil moisture 30 centimeters below the surface.