Large-scale temporal and spatial imaging of soil brightness temperature with an L-band synthetic aperture microwave radiometer

• Main Author: Isham, John D
• Language: ENG
• Published: ScholarWorks@UMass Amherst 1999
• Subjects: Electrical engineering|Hydrology|Remote sensing
• Online Access: https://scholarworks.umass.edu/dissertations/AAI9920615

The Microwave Remote Sensing Lab (MIRSL) at the University of Massachusetts has developed a second-generation L-band synthetic aperture microwave radiometer referred to as the Electronically Steered Thinned Array Radiometer, or ESTAR, which measures soil moisture or ocean salinity from an airborne platform. This dissertation reviews the basics of synthetic aperture microwave radiometry, then details recent modifications to the ESTAR instrument, including the change to a horizontally polarized antenna, and improvements to the instrument's thermal control. The dissertation discusses calibration methods, including corrections to the null feedback radiometer (NFR) data used to form the system response matrix, or G-matrix. It also describes image calibration, noting steps taken to reduce image ripple. Results obtained during the Southern Great Plains 1997 (SGP'97) hydrology experiment in Oklahoma are discussed and compared to rainfall data obtained from the Oklahoma Mesonet system of weather stations. This data set is the largest one of its type obtained by ESTAR to date, in terms of area of geographical and temporal coverage.