Ionospheric Electron Density Reconstruction Based on Space-Borne SAR in Alaska Regions

The use of low-frequency spaceborne fully polarized synthetic aperture radar (SAR), such as the ALOS PALSAR, to detect the structure of ionospheric has been widely validated in recent years. In terms of total electron content (TEC) retrieval, SAR exhibits significant advantages over GPS with regard to both accuracy and resolution at high latitude. However, TEC cannot reflect the vertical structure of the ionosphere and still has limitations. On this basis, this letter presents a study into the application of fully polarimetric PALSAR in computerized ionospheric tomography (CIT), which extends the horizontal ionospheric structure to the vertical, i.e., the 3-D ionospheric electron density (IED) distribution. The reconstruction results from three groups of PALSAR measured data in Alaska are compared with the results from the nearby incoherent scatter radar (ISR). The accuracy has improved by 28.9%, 33.2%, and 47.6%, respectively, compared to the ionosphere model. This shows that the PALSAR has the ability to not only determine the horizontal structure of the ionosphere but also accurately reconstruct the 3-D IED, making it a promising approach for ionosphere sounding at high latitude.