Frequency dependence of ionospheric scintillations and its application to spectral estimation of electron density irregularities

Abstract

Analytical results of simultaneous observations of 136 MHz and 1.7 GHz ionospheric scintillations at mid-latitude during summer are presented. The causal relation between scintillation occurrence and ionospheric condition is discussed to examine the influences of spread- F and sporadic- E on the scintillation. The diurnal variations of scintillation occurrences show that the time of maximum occurrence for the nighttime scintillation depends on the scintillation amplitude. The frequency dependence of the scintillation depth is, on the average, f t −1.38 during nighttime and f t −1.52 during daytime, where f t , is the transmitted wave-frequency, which may reflect the difference in the spectral form of electron density irregularities. Finally, the temporal variations of the frequency dependence index are investigated for the nighttime period. The result indicates a clear variation of the spectral form of irregularities with time.