Research On Datong Surface Deformation Monitoring With Short Spatio-temporal Baseline PS-InSAR Technology

As a new promising remote sensing technique, satellite synthetic aperture radar interferometry (InSAR) has been developed rapidly in recent twenty years, Its differential mode (D-InSAR), can be applied to detect ground deformation with the advantages of all-weather, large-scale and high accuracy, which provides a new space-geodetic approach for ground deformation disaster monitor. However, Its applications has been limited by the factor of spatio-temporal decorrelation and stmospheric effect. The PS-InSAR technique which developed in recent years can overcome the limited factors, the operation objects of this technique are permanent scatters point targets, which can keep phase stable in the temporal series, and these point targets can be used to get surface subsidence by analyzing the times-series differential phase variation.The basic principles of InSAR and the composition of the interferometric phase were introduced. The deformation monitoring principle and processing procedure of D-InSAR, the error sources and restricted factors were analyzed. In addition, the space differential phase model has been established based on the D-InSAR technology and the key technology of PS-InSAR data processing were introduced.Considering characteristics of the stable backscatters and high SNR of PS point targets, multi- thresholding algorithm is proposed to detect PS point targets. In this paper,39 SAR images covered Datong area has been used to select PS point targets which distributed reasonably. It proved the reliability of identification the PS point targets which used multi-thresholding algorithm.Compared with the D-InSAR, SBAS technology has its own unique advantages in deformation monitoring. It also can overcome the phenomenon of spatio-temporal decorrelation effectively, and the number of images is not high demanded because it increased time sampling rate. The principle of SBAS deformation monitoring was introduced. We took 39 SAR images to obtain the seven years of time series deformation of Datong region. However, the SBAS technology has the defects in the losing of resolution, and failed to take account of atmosphere effect.In order to solve the problem of PS-InSAR technology in the data number, we merged SBAS with PS-InSAR technology, which called short spatio-temporal baseline PS-InSAR technology. We also use 39 Envisat SAR images to obtain the seven years accumulation deformation which from 2003 to 2010 in Datong area, the results show that the largest annual average deformation rate had reached 2.2cm/a, and the results of deformation is highly consistent with the results of the SBAS technology and the PS-InSAR technology.At the same time, we used short spatio-temporal baseline PS-InSAR technology to detect the accumulated time series deformation in Datong by 20 SAR images, the deformation result has the same accuracy with the PS-InSAR technology which used 39 SAR images, the test proved that the short spatio-temporal baseline PS-InSAR technology can overcome the disadvantages of high demanding of SAR images in PS-InSAR technology to some degree. At the same time, it can ensure the accuracy and the reliability of the deformation results. It also extends the applications of PS-InSAR technology and with strong practicability.