title: Estimation of Atmospheric Path Delays in TerraSAR-X Data using Models vs. Measurements.
abstract: 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.
authors.affiliation: Department of Geography, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland. michael.jehle@geo.uzh.ch.
authors.forename: Michael
authors.initials: M
authors.lastname: Jehle
authors.affiliation: Institute of Geodesy and Photogrammetry, ETH Zurich, HPV G56, Schafmattstrasse 34, CH-8093 Zurich, Switzerland. donat.perler@geod.baug.ethz.ch.
authors.forename: Donat
authors.initials: D
authors.lastname: Perler
authors.affiliation: Department of Geography, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Small
authors.affiliation: Department of Geography, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Schubert
authors.affiliation: Department of Geography, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland. erich.meier@geo.uzh.ch.
authors.forename: Erich
authors.initials: E
authors.lastname: Meier
keywords: SAR; Synthetic aperture radar; TerraSAR-X; atmosphere; calibration; geolocation accuracy; ionosphere; path delay; troposphere