Simultaneous small and large scale irregularities in the ionospheric F region

Abstract

THE study of scintillation-producing irregularities over Australasia indicates a continuous spectrum of scale sizes of ionisation clouds¹. Amplitude scintillations are most sensitive to small scale irregularities, peaking at 1 km transverse to the magnetic field^1,2. The presence of large scale irregularities could be detected from the measurements of total electron content (TEC), using the Faraday rotation or dispersive-Doppler technique, on v.h.f./u.h.f. transmissions from satellites orbiting the Earth. There is considerable evidence of large wave structures in the F region; the wavelength and period of large ionospheric disturbances are similar to those of large scale gravity waves^3,4.