CHARACTERISTICS OF SMALL-SCALE IONOSPHERIC IRREGULARITIES AS DEDUCED FROM SCINTILLATION OBSERVATIONS OF RADIO SIGNALS FROM SATELLITES ETS-2AND POLAR-BEAR-4 AT IRKUTSK

This paper presents some new results on the small-scale inhomogeneous ionospheric structure obtained at a facility for spaced-antenna recept ion of transionospheric signals from ETS-2 and Polar Bear 4 near Irkut sk (Eastern Siberia, 52-degrees-N, 104-degrees-E). A technique based o n transferring time spectra of scintillations to spatial spectra using measured horizontal irregularity drift velocities is used to obtain a n estimate of the mean spatial spectrum of midlatitude scintillations. Two different methods were used to determine the inclination index of the scintillation spectrum, which was found to be equal to -2, in agr eement with the value recently predicted for small-scale F region irre gularities generated through mapping of small-scale, turbulent electri c fields from the E region to the F region. Drift velocities of the di ffraction pattern, and also the altitudes at which ionospheric irregul arities are located, agree well with results obtained by other authors for midlatitudes. Using simultaneous measurements for a geostationary satellite and an orbiting satellite, the supposition about the existe nce of the southern boundary of the scintillation region has been conf irmed. Finally, analysis of quasi-periodic (QP) scintillations and sim ultaneously determined diffraction pattern velocities is used to show that the height of isolated irregularities giving rise to QP scintilla tions corresponds to the maximum of the ionospheric F2 region.