Correcting Atmospheric Effects on the InSAR Measurements using GPS Data

Abstract

The effect of the atmospheric error in the spaceborne synthetic aperture radar (SAR) signal is more prominent in Malaysia due to its hot and wet conditions. Because the atmospheric error is believed to happen constantly in space and randomly in time, low-pass filtering in space and high-pass filtering in time is employed to measure it. However, with few scenes, the filtering technique’s reliability in removing atmospheric error may be insufficient, leading to erroneous surface deformation. Therefore, an external atmospheric correction needs to be modelled to improve the accuracy of surface deformation. In this study, the atmospheric error correction was estimated from GPS and applied to the deformation analysis. The result shows that the atmospheric error level estimated from the filtering technique was –6.9 to 7.5 radians, while using GPS was -1.0 to 1.9 radians. After using the filtering process, the rate of deformation fell dramatically. However, compared to the reference deformation, the rate was too low, indicating that the filtering technique overstated the level of atmospheric error. At many data collections, the atmospheric correction calculated from GPS gave deformation values closer to the reference deformation. Hence, this study will help the researchers to model the atmospheric correction over the Malaysia region in future.

Associations between Surface Deformation and Groundwater Storage in Different Landscape Areas of the Loess Plateau, China

“…Then, the interferogram was generated (Figure 2b,c, taking the fifth image position as an example). Taking the first scene image of each orbit in January 2020 as the super main image, 83,85,84,86,89,87,89,84,79,85, and 87 interference pairs were generated, respectively. After eliminating the interferograms with poor coherence, a multi-view coefficient of 1:5 was set in the range and azimuth directions to improve the processing interference quality.…”

“…The climatic environment of the Kubuqi Desert features large temperature differences and high wind speeds and is characterized by frequent turbulence and scattering phenomena, thereby increasing atmospheric errors [86]. Even when atmospheric error corrections are added or interferometric pairs with atmospheric errors are removed, tropospheric errors are still not completely negligible [87]. After temporal cubic spline interpolation to produce a temporal resolution of 1 month, studies have shown that time scale interpolation can have a degrading effect on the accuracy of the results [88].…”