Can spaceborne synthetic aperture radar be useful for the mapping of ionospheric disturbances in the Arctic Region?

In this work we study the potential of C-band SAR images to map ionosphere disturbances in the Arctic region. This region is a unique region for ionosphere studies due to the characteristics of the geomagnetic field. In particular, we focus on the SAR interferometry technique as means to measure the temporal variation of propagation delay in correspondence of ionosphere disturbances. This technique provides maps of propagation delay differences between the acquisition dates of the two coherent SAR images needed to estimate the propagation delay over the study area. The high spatial resolution of C-band SAR images, in the order of 25 meters could contribute to the study of spatial distribution of ionosphere disturbances. Digisondes, VLF/ELF receivers and the EISCAT radars in the available in the Arctic region provide the time of ionosphere disturbances due to the solar activity, monitored by the ACE satellite. This allows to select the SAR images to process to map the ionosphere disturbances. The typical spatial coverage and acquisition times of Sentinel-1 images over the Arctic region are reported. A numerical analysis is carried out to estimate the expected ionosphere propagation delay in Sentinel-1 interferograms and so the potential of SAR interferometry to map the effects of ionosphere disturbances

A Novel Strategy of Ambiguity Correction for the Improved Faraday Rotation Estimator in Linearly Full-Polarimetric SAR Data

Spaceborne synthetic aperture radar (SAR) missions operating at low frequencies, such as L-band or P-band, are significantly influenced by the ionosphere. As one of the serious ionosphere effects, Faraday rotation (FR) is a remarkable distortion source for the polarimetric SAR (PolSAR) application. Various published FR estimators along with an improved one have been introduced to solve this issue, all of which are implemented by processing a set of PolSAR real data. The improved estimator exhibits optimal robustness based on performance analysis, especially in term of the system noise. However, all published estimators, including the improved estimator, suffer from a potential FR angle (FRA) ambiguity. A novel strategy of the ambiguity correction for those FR estimators is proposed and shown as a flow process, which is divided into pixel-level and image-level correction. The former is not yet recognized and thus is considered in particular. Finally, the validation experiments show a prominent performance of the proposed strategy

A Novel Strategy of Ambiguity Correction for the Improved Faraday Rotation Estimator in Linearly Full-Polarimetric SAR Data

Spaceborne synthetic aperture radar (SAR) missions operating at low frequencies, such as L-band or P-band, are significantly influenced by the ionosphere. As one of the serious ionosphere effects, Faraday rotation (FR) is a remarkable distortion source for the polarimetric SAR (PolSAR) application. Various published FR estimators along with an improved one have been introduced to solve this issue, all of which are implemented by processing a set of PolSAR real data. The improved estimator exhibits optimal robustness based on performance analysis, especially in term of the system noise. However, all published estimators, including the improved estimator, suffer from a potential FR angle (FRA) ambiguity. A novel strategy of the ambiguity correction for those FR estimators is proposed and shown as a flow process, which is divided into pixel-level and image-level correction. The former is not yet recognized and thus is considered in particular. Finally, the validation experiments show a prominent performance of the proposed strategy