Calibration of the Shuttle Radar Topography Mission using point and distributed targets

The Shuttle Radar Topography Mission (SRTM) will provide detailed topographical maps for about 80% of the Earth´s surface. SRTM consists of single-pass C-and X-band interferometric synthetic aperture radars (INSARs). In order to apply SRTM data to remote sensing applications the data must be calibrated. This paper presents the University of Michigan´s recent SRTM calibration campaign. A calibration array, consisting of point and distributed targets, was deployed with the intention of determining the accuracy of INSAR-derived digital elevation maps and performing radiometric calibration of backscatter data. The array spanned one of the X-band swaths and stretched from Toledo, Ohio to Lansing, Michigan. Passive and active targets were used. The passive targets included trihedrals and tophats. Backscatter measurements at Cand X-bands of an extensive plowed field were also made for distributed target calibration. The measurements of the field were acquired by a truck-mounted radar system. The locations in latitude, longitude, and elevation of the point targets were determined using differential GPS for interferometric phase calibration. As soon as the processed calibration swaths are available, the data taken during the campaign will be used for radiometric and phase calibration. The resulting calibration will supplement those performed by JPL and DLR