Estimation of Atmospheric Path Delays in TerraSAR-X Data using Models vs. Measurements

• Main Authors: Donat Perler, Michael Jehle, David Small, Adrian Schubert, Erich Meier
• Format: Article
• Language: English
• Published: MDPI AG 2008-12-01
• Series: Sensors
• Subjects: Synthetic aperture radar; SAR; atmosphere; troposphere; ionosphere; path delay; geolocation accuracy; calibration; TerraSAR-X
• Online Access: http://www.mdpi.com/1424-8220/8/12/8479/

Spaceborne synthetic aperture radar (SAR) measurements of the Earth’s surface depend on electromagnetic waves that are subject to atmospheric path delays, in turn affecting geolocation accuracy. The atmosphere influences radar signal propagation by modifying its velocity and direction, effects which can be modeled. We use TerraSAR-X (TSX) data to investigate improvements in the knowledge of the scene geometry. To precisely estimate atmospheric path delays, we analyse the signal return of four corner reflectors with accurately surveyed positions (based on differential GPS), placed at different altitudes yet with nearly identical slant ranges to the sensor. The comparison of multiple measurements with path delay models under these geometric conditions also makes it possible to evaluate the corrections for the atmospheric path delay made by the TerraSAR processor and to propose possible improvements.