Temporarily Coherent Point SAR Interferometry.

摘要

Spaceborne Interferometric Synthetic Aperture adar (InSAR) has been proven very useful in assessing remotely ground displacements. InSAR measurements have contributed to better understanding of the processes and mechanisms of geohazards such as earthquakes, volcanoes and landslides. There are two major error sources in InSAR measurements, i.e., decorrelation due to temporal and geometric effects and phase errors introduced by spatial and temporal variations of the atmosphere. The error sources can in extreme cases render the InSAR technology useless.;A novel InSAR data analysis method termed Temporarily Coherent Point InSAR (TCPInSAR) is proposed in the thesis. The method can estimate deformation parameters reliably by avoiding the process of phase ambiguity estimation. Included in the method are a series of innovations. To improve the density of TCPs, especially in areas with a small set of SAR images, we have developed a new TCP identification method based on offset statistics. To make sure the TCPs can be connected extensively we have proposed an efficient point connection strategy that performs Delaunay triangulation locally. To retrieve the deformation rates reliably we have designed a least squares estimator with an outlier detector that can remove the arcs with phase ambiguities efficiently. To better consider the quality of individual interferograms we have improved the method of variance covariance estimation under the framework of least squares.;After validating TCPInSAR technique using simulated datasets, we have applied the TCPInSAR method to the Los Angeles basin in southern California where structurally active faults such as Newport-Inglewood fault are believed capable of generating damaging earthquakes. Both the estimated long-term average subsidence and seasonal deformation in the basin are in good agreement with GPS observations from the Southern California Integrated GPS Network (SCIGN), indicating that the TCPInSAR method is effective for the retrieval of ground motions especially in areas where abundant multi-temporal SAR data are available and dense coherent points can be isolated. To demonstrate the performance of TCPInSAR method on changing landscapes where both the persistently and partially coherent points are available, we also applied the method to the southern part of Macau which is undergoing fast redevelopment.