Measurement of ionospheric scintillation parameters from SAR images using corner reflectors

Space-based low-frequency (L-band and below) synthetic aperture radar (SAR) isaffected by the ionosphere. In particular, the phase scintillation causes the sidelobesto rise in a manner that can be predicted by an analytical theory of the point spreadfunction (PSF).In this paper, the results of an experiment, in which a 5 m corner reflector onAscension Island, was repeatedly imaged by PALSAR-2 in the spotlight mode aredescribed. Many examples of the effect of scintillation on the SAR PSF wereobtained, and all fit the theoretical model. This theoretical model of the PSF has thenbeen used to determine two ionospheric turbulence parameters, p and C_kL, from theSAR PSF. The values obtained have been compared with those obtained fromsimultaneous GPS measurements. Although the comparison shows that the twomeasures are strongly correlated, the differing spatial and temporal scales of SARand GPS make exact comparison difficult.