SIR-C DATA QUALITY AND CALIBRATION RESULTS

The SIR-C/X-SAR imaging radar took its first flight on the Space Shutt le Endeavour in April 1994 and flew for a second time in October 1994. This multifrequency radar has fully polarimetric capability at L- and C-band, and a single polarization at X-band (X-SAR). The Endeavour mi ssions were designated the Space Radar Laboratory-1 (SRL-1) and -2 (SR L-2), Calibration of polarimetric L- and C-band data for all the diffe rent modes SIR-C offers is an especially complicated problem, The solu tion involves extensive analysis of pre-flight test data to come up wi th a model of the system, analysis of in-flight test data to determine the antenna pattern and gains of the system during operation, and ana lysis of data from over fourteen calibration sites distributed around the SIR-C/X-SAR orbit track. The SRL missions were the first time a mu ltifrequency polarimetric imaging radar employing a phased array anten na has been flown in space. Calibration of SIR-C data products involve d some unique technical problems given the complexity of the radar sys tem. in this paper, the approach adopted for calibration of SIR-C data is described and the calibration performance of the data products is presented.