Monitoring Great Lakes ice cover with satellite synthetic aperture radar (SAR)

During the 1997 winter season, shipborne polarimetric backscatter measurements of Great Lakes ice types using the Jet Propulsion Laboratory (JPL) C-band scatterometer, together with surface-based ice physical characterization measurements and environmental parameters were acquired concurrently with RADARSAT and ERS-2 SAR data. Using a supervised classification algorithm, measured backscatter values (converted to dB) for three ice types and calm water were applied to an 8×8 pixel averaged ERS-2 calibrated SAR image. Certain assumptions were made on the local incidence angle, one of which was that any change in incidence angle across a distributed target was neglected, i.e. a distributed target corresponds to one average value of the incidence angle (23° was used). Although the calculated overall uncertainty was about +/-1 dB as a result of the averaging and incidence angle effect, an algorithm to correct for power loss and local incidence angle effect is applied in this study to the ERS-2 image, resulting in a more accurate classification