Measurement of Ionospheric Scintillation Parameters From SAR Images Using Corner Reflectors

Space-based low-frequency (L-band and below) synthetic aperture radar (SAR) is affected by the ionosphere. In particular, the phase scintillation causes the sidelobes to rise in a manner that can be predicted by an analytical theory of the point spread function (PSF). In this paper, the results of an experiment, in which a 5 m corner reflector on Ascension Island, was repeatedly imaged by PALSAR-2 in the spotlight mode are described. Many examples of the effect of scintillation on the SAR PSF were obtained, and all fit the theoretical model. This theoretical model of the PSF has then been used to determine two ionospheric turbulence parameters p and C
_k
L from the SAR PSF. The values obtained have been compared with those obtained from simultaneous GPS measurements. Although the comparison shows that the two measures are strongly correlated, the differing spatial and temporal scales of SAR and GPS make exact comparison difficult.