Effect of Anisotropy on Ionospheric Scintillations Observed by Synthetic Aperture Radar (Sar)

Spaced-based synthetic aperture radar (SAR) operating at low frequencies and capable of earth observation are affected by the layer of ionosphere. The interaction of the signal with the irregularity layer degrades and distorts the SAR image quality. The accurate assumption of size of the irregularities, defined by the axial ratio, in determining the effects of scintillation on the signal is critical. In the present work, the authors have compared the impact of different axial ratios on a pair of SAR images over the Indian subcontinent to estimate scintillation and ionospheric parameters. The parameters are then compared with the available ground-based measurements to determine the precise size of irregularity structure. The amplitude scintillation index, S4, estimated from the Global Positioning Satellite (GPS) receivers for two Indian stations of Tirunelveli and Rajkot are used in this study. The assumption of axial ratio value is 60: 1 to estimate the parameters was found to correctly fit into the model.