Persistent Scatterer InSAR using Artificial Point Targets – First Analysis of Amplitude and Phase Stability
Franz Meyer(1), Don Atwood(1), Wade Albright(1) and Gabor Varga(1)
(1) Geophysical Institute, University of Alaska Fairbanks, Faribanks, Alaska, 99775, United States
The potential of InSAR for topographic mapping and long-term deformation monitoring has been extensively proven over the last decade and has been widely recognized throughout the scientific community. However, its value and applicability to geodynamic monitoring problems is severely limited by the influence of temporal decorrelation and electromagnetic path delay variations. The invention of the multi-image Persistent Scatterer Interferometry (PSI) technique in the late 1990’s was a big step forward for high accuracy observations of slow surface motion and object deformation over long temporal time spans. It enables the identification, isolation, and estimation of millimeter surface deformation processes from space, independent of atmospheric effects such as tropospheric water vapor. This approach proves to be particularly suitable for the observation of the deformation regimes of cities and other build-up areas, but has difficulties in rural areas where the density of point-like scatterers is low.
The Alaska Satellite Facility (ASF) developed a new corner reflector concept that will facilitate PSI in vegetated non-urban areas. The reflectors are small in size (1m – 1.3m), cheap, and easy to deploy, and are, therefore, perfectly suited to serve as artificial point targets in areas sparsely populated by natural PS. A test field has been established at ASF to test both the amplitude and phase stability of the artificial Permanent Scatterers in natural environment. A stack of ERS and RADARSAT data has been acquired and a PS analysis of the test field was performed.
Besides discussing the design, price, and deployment of the artificial point targets, this presentation will present a quality assessment of their amplitude and phase stability, which defines their suitability for PSI. The analysis of the SAR stack shows a good agreement of the artificial reflectors with the surrounding natural PS. Influences of wind and snow on some of the interferometric phase measurements derived from the artificial point targets will be discussed. Different mounting techniques for artificial PS will be presented, each tailored for a specific geophysical problem. A description of ongoing projects will conclude the paper.
Keywords: ESA European
Space Agency - Agence spatiale europeenne,
observation de la terre, earth observation,
satellite remote sensing,
teledetection, geophysique, altimetrie, radar,
chimique atmospherique, geophysics, altimetry, radar,