Effects of variation in soil moisture on ERS-1 SAR backscatter

Under wet soil conditions, the European Remote Sensing Satellite (ERS-1) synthetic aperture radar (SAR) backscatter from open short-grass fields of 0.05 kg/m/sup 2/ biomass is equal to or greater than that from the loblolly pine stands (<15 years-old) at Duke Forest, North Carolina, USA. Under dry soil conditions, the backscatter increased about 2-3 dB as the biomass increased from 0.05 kg/m/sup 2/ to 0.5-1.5 kg/m/sup 2/, and the backscatter may be saturated near a 0.5-1.5 kg/m/sup 2/ biomass level. Signal saturation at low standing biomass and high sensitivity to soil moisture conditions limit the value of the ERS-1 SAR for forest monitoring.<<ETX>>