Analysis and correction of spatial variant background ionosphere impacts on single-pass InSAR system

• Main Authors: Lei Yu, Yongsheng Zhang, Anxi Yu, Zhen Dong, Jinhui Li, Yifei Ji
• Format: Article
• Language: English
• Published: Wiley 2019-08-01
• Series: The Journal of Engineering
• Subjects: ionospheric electromagnetic wave propagation; spaceborne radar; radar interferometry; radiowave propagation; synthetic aperture radar; remote sensing by radar; radar imaging; faraday effect; conventional ionosphere spatial invariant model; insar system operating; insar measurements; repeat-pass interferometry synthetic aperture radar system; spatial variant background ionosphere; international reference ionosphere; insar products; single-pass insar measurement; spatial variant ionosphere; low-earth orbit insar system; space-borne single-pass insar system
• Online Access: https://digital-library.theiet.org/content/journals/10.1049/joe.2019.0395

Compared with the repeat-pass interferometry synthetic aperture radar (InSAR) system, the single-pass InSAR system, such as TanDEM-X and TanDEM-L, has better performance and less decorrelation. However, InSAR measurements can be seriously influenced by the background ionosphere, especially for InSAR system operating at lower frequencies, such as L-band and P-band. Low-frequency signals propagating in the ionosphere suffer serious group delay, dispersion, scintillation and Faraday rotation, which further induce the image shift and decorrelation of SAR interferometry pairs. Since the ionosphere shows significant space-varying and time-varying features, the conventional ionosphere spatial invariant model is invalid for space-borne single-pass InSAR system. It is supposed that the time variance of ionosphere in short integration time can be neglected for low-earth orbit InSAR system. The effect of the spatial variant ionosphere on single-pass InSAR measurement is analysed and a correction method for InSAR products based on the prior knowledge is presented in this paper. Simulations are performed by using total electron content data obtained from the international reference ionosphere model, and the results indicate the significant error induced by spatial variant ionosphere.