Potential of geosynchronous SAR interferometric measurements in estimating three-dimensional surface displacements

The ability of differential interferometric synthetic aperture radar (DInSAR) technology used for centimeter level deformation detection has been well-proved. Nevertheless, the applications of DInSAR under the low Earth orbit (LEO) are limited to the line-of-sight (LOS) measurements, the limited observation area and the long revisited time. Geosynchronous SAR (GEO SAR), which runs in the height of 36000 km with the advantage of a short revisit time and a large observation area, is a potential approach to overcome the series problems in LEO SAR. This paper focuses on estimating three-dimensional (3D) displacements by using GEO SAR DInSAR measurements acquired from multiple imaging geometries. Aiming to provide a normal solution for geologic hazard monitoring and relative geophysical application in the future, the errors induced by decorrelation noise, orbital ramp and ionospheric distortion are analyzed for the GEO SAR DInSAR measurements. A series of experiments have been conducted to find the relationship between the 3D displacements and the DInSAR observations which are provided with different noises and combinations of imaging geometries. The results reveal that 3D displacements can be expected from the combination of left-and right-looking GEO SAR DInSAR measurements. In particular, the north-south solution can achieve centimeter and even millimeter level.