\ Institute of Space and Earth Information Science, CUHK

A Study on ERS-ENVISAT Coherent Integration in Satellite Persistent Scatterers Interferometry

Principal Investigator: Dr. Jiang Liming

Start Date: 2008/01/01
End Date: 2009/12/31
Type of Grant: Direct Grant for Research (2007-2008) íV 1st Round

Urban ground deformation (e.g. subsidence or landslide) is a serious environmental hazard associated with rapid urbanization in many parts of the world and more than 70 cities in China are undergoing natural or human-induced land surface subsidence.

Compared with traditional ground-based surveys (e.g. GPS and spirit leveling), satellite Persistent Scatterers Interferometry (PSI) is a very promising remote sensing technology that offers low cost, large-coverage deformation monitoring and up to millimeter accuracy by exploiting long series of SAR data acquired over the same monitoring area. Due to the outstanding availability of data more than 12 years, PSI has been mostly and successfully applied to a time series of SAR data acquired by compatible radar sensors of the European Remote Sensing Missions ERS-1 and ERS-2. But the ERS-1 mission ended in year 2000 and unfortunately, recent ERS-2 SAR acquired images are no longer suitable for interferometric applications due to the failures of gyros since later 2001. With the launch in 2002 of ERS-2 successor, ENVISAT satellite, therefore updating ERS-based PSI measurements by means of the Advanced SAR (ASAR) data of ENVISAT mission became a major issue. Moreover, in many cases the current time PSI monitoring is in the center of the interest, but the existence of the ERS archive is relevant as a record of the deformation history. Another important factor is that the reliability and accuracy of current time monitoring with ASAR is improved by the availability of the historic ERS observations, this particularly in cases where only few ASAR images were acquired. For these reasons, it is extremely important to study ERS-ENVISAT coherent integration in PSI analysis for the continuity of ERS-based deformation measurement and the improvement of ASAR-based monitoring accuracy.