High-Resolution Measurement of Soil Moisture from Insar Phase Closure

InSAR (interferometric synthetic aperture radar) phase closure, the net phase from linking three multilooked interferograms formed from three acquisitions, has been linked to soil moisture [1]. Here, we show one possible way to predict soil moisture from InSAR phase closure. Our data reduction approach includes an integration of the phase closure over time and subtraction of a random walk component to relate the differential phase values to soil moisture level. We find that for a large test region of Oklahoma, the integrated phase closure using Sentinel-1 data tracks the soil moisture observed in the field. In other cases, the match is less than good. If we can determine under what circumstances these InSAR measurements provide a good match to soil moisture, we have a valuable utility to remotely estimate soil moisture at scales useful for agricultural assessments, as conventional radiometric measurements cover hundreds of adjacent fields in each resolution cell.