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Monitoring subsidence with short-term InSAR image stack

Mingsheng Liao(1), Lijun Lu(1), Changchen Wang(1), Teng Wang(1) and Xin Tian(1)

(1) Wuhan University, 129 Luoyu Road, 430079 Wuhan, China

Abstract

The Permanent Scatterer interferometry(PS-InSAR) has been recognized as a powerful tool for monitoring long-term surface deformations in urban areas. Due to the fact that a large number of images (normally >30 scenes) are required to identify stable PS points and extract reliable deformation information, its application is limited in operational case where only large image stack is available. In this presentation, a method for deriving stable point targets in small SAR image stack is proposed to extend the application of PS-InSAR technique.

As we known, identification of stable pointwise target is a key procedure in SAR image interpretation and surface deformation monitoring application. Generally for long-term InSAR dataset, stable pointwise target is characterize by stable scattering mechanism and unaffected by either geometrical or temporal decorrelation in time series. So far there are mainly two kinds of methods to identify the stable pointwise target. One is based on their temporal stability to derive extraction index of stable pointwise target in long time series, such as PS (Permanent Scatter) and CTM (Coherent Target Model) approach. Another one is spectral correlation analysis method which may provide us a new effective way to identify pointwise targets with a limited number of observation or even without temporal baseline on basis of characteristics of single image itself, such as CSs (Coherent Scatters) approach.

In this presentation, spectral correlation analysis is applied in azimuth dimension of SAR image. The sublook correlation products of SAR image are obtained in azimuth spectrum by which stable pointwise targets could be identified. After extraction of stable point-wise targets even with very small image stacks, the surface deformation can be derived on these targets. A small ASAR dataset acquired from 2003 to 2005 in Shanghai are used for case study. The data collection was supported by ESA-China DRAGON Programme. The final deformation products are validated by comparing with ground leveling data. The result proves that the method can be applied in small dataset with high flexibility and the precision of subsidence result can meet practical construction project requirements.

Keywords: stable pointwise target´╝îsublook correlation´╝îsurface deformation, PS-InSAR.

 

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, atmospheric chemistry