Abstract
Persistent scatterers interferometric Synthetic Aperture Radar (PS-InSAR) is capable of precise topography measurement up to sub-meter scale and monitoring subtle deformation up to mm/year scale for all the radar image pixels with stable radiometric characteristics. As a representative PS-InSAR method, the Stanford Method for Persistent Scatterers (StaMPS) is widely used due to its high density of PS points for both rural and urban areas. However, when it comes to layover regions, which usually happens in urban areas, the StaMPS is limited locally. Moreover, the measurement points are greatly reduced due to the removal of adjacent PS pixels. In this paper, an improved StaMPS method, called IStaMPS, is proposed. The PS pixels are selected with high density by the improved PS selection strategy. Moreover, the topography information not provided in StaMPS can be accurately measured in IStaMPS. Based on the data acquired by TerraSAR-X/TanDEM-X over the Terminal 3 E (T3 E) site of Beijing capital international airport and the Chaobai River of Beijing Shunyi District, a comparison between StaMPS-retrieved results and IStaMPS-retrieved ones is performed, which demonstrates that the density of PS points detected by IStaMPS is increased by about 1.8 and 1.6 times for these two areas respectively. Through comparisons of local statistical results of topography estimation and mean deformation rate, the improvement granted by the proposed IStaMPS is demonstrated for both urban areas with complex buildings or man-made targets and non-urban areas with natural targets. In terms of the spatio-temporal deformation variation, the northwest region of T3 E experienced an exceptional uplift during the period from Jun. 2012 to Aug. 2015, and the maximum uplift rate is approximately 4.2 mm per year.
Highlights
Space-based technology is an efficient way to reconstruct 3D topography and monitor both natural and man-made disasters, such as earthquakes [1,2,3], volcanoes [4,5,6,7], landslides [8,9,10,11], and anthropogenic subsidence or uplift due to fluid withdrawal or injection [12,13,14,15]
Due to lack of accurate topography measurement in Stanford Method for Persistent Scatterers (StaMPS), the estimation method presented in Section 2.3 was used to retrieve the topography and deformation information for both the studied urban and non-urban areas
The maximum stds of the first and the last observations are 0.31 mm/year and 0.27 mm/year for StaMPS, and 0.36 mm/year and 0.38 mm/year for the proposed IStaMPS. These results clearly demonstrate the advantage of IStaMPS over StaMPS for non-urban areas
Summary
Space-based technology is an efficient way to reconstruct 3D topography and monitor both natural and man-made disasters, such as earthquakes [1,2,3], volcanoes [4,5,6,7], landslides [8,9,10,11], and anthropogenic subsidence or uplift due to fluid withdrawal or injection [12,13,14,15]. Each pixel in PSCs is tested for phase stability by temporal coherence Those whose phase variation fits into the assumed deformation model are deemed stable. These methods have been very successful in detecting PS pixels and investigating topography of urban areas. The quantity of PS pixels in urban areas has further increased for the recently proposed Iterative PS-InSAR method (IPSI) [32]. The distance of neighboring PS pixels is so large that the absolute value of unmodeled phase resulting from spatial atmosphere and deformation difference exceeds π in phase unwrapping. Due to the inaccurate deformation model, many stable pixels in natural areas are dropped from PSCs, which leads to a small density of PS and a large distance between neighboring PS pixels
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