Calibration results for J-ERS-1 SAR data produced by the Alaska SAR Facility

The Alaska SAR Facility has been receiving and processing SAR data from the J-ERS-1 satellite since Spring 1992. Corner reflectors have been set up for J-ERS-1 SAR calibration at a site near Delta Junction, in central Alaska. Image quality and calibration analysis results from the Delta Junction site and others are presented. The impact of the 3-bit analog-to-digital converter and the automatic stepping of the gain as a function of range in the J-ERS-1 radar receiver on calibration performance has been assessed. Preliminary observations on J-ERS-1 SAR data are that the average signal-to-noise ratio is generally fairly low, in the range 5-6dB. Azimuth ambiguity levels are higher than preflight analysis indicated. Over land, the dynamic range in the backscatter at L-band for ~36 degree incidence angle is often fairly high. Thus example J-ERS-1 SAR images of vegetated areas, such as tropical rain forests or boreal forests show greater contrast than their counterparts from the European ERS-1, which images at C-band with ~23 degree incidence angle. Part of the research described in this paper was carried out by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the NASA