Small-scale ionospheric irregularities produce numerous observed effects during high-frequency radio wave sounding from a satellite. Scattering of z-mode waves radiated by an ionosonde, which results in the occurrence of characteristic traces on ionograms, are among the most complex of them. In the present paper the factors determining the power characteristics of such signals are considered. These are the size and shape of the surface of orthogonality for a family of z-mode waves radiated from a satellite, features of the radiating and propagating radio waves in a non-uniform magnetized plasma, and the details of the scattering process. Simple but adequate physical models for each of these factors are presented and a numerical calculation algorithm of the power of the z-mode scattered signals received by the satellite sounder receiver has been constructed. Values for this calculated quantity are presented as a function of time delay, sounding frequency, and magnetic latitude. A synthesis of topside ionograms showing z-mode scattered traces has been performed. The results support new diagnostic methods of detecting small-scale ionospheric irregularities using topside-sounder z-mode signal returns and the concept that the sounder radiation can, under certain conditions, stimulate artificial plasma turbulence. In addition, it was shown that z-mode scattering may contribute to the resonance observed at the plasma frequency on topside ionograms.

We present initial findings of a topside sounder technique used to investigate global distribution of small-scale (tens and hundred of meters) irregularities in the ionosphere. We use the observations of the COSMOS-1809 topside sounder based on a study of the properties of scattered slow extraordinary waves (Z-mode) which are induced by topside sounder emission. The signature of the received signals are interpreted in terms of irregularity-intensity distributions. The size of the irregularity-localization region is of the order of several tens of kilometers from the satellite. We present our initial results and show that they compare favorable with known characteristics of F-region peak latitudinal irregularity distributions obtained for irregularities with larger scales

We present initial findings of a topside sounder technique used to investigate global distribution of small-scale (tens and hundred of meters) irregularities in the ionosphere. We use the observations of the COSMOS-1809 topside sounder based on a study of the properties of scattered slow extraordinary waves (Z-mode) which are induced by topside sounder emission. The signature of the received signals are interpreted in terms of irregularity-intensity distributions. The size of the irregularity-localization region is of the order of several tens of kilometers from the satellite. We present our initial results and show that they compare favorable with known characteristics of F-region peak latitudinal irregularity distributions obtained for irregularities with larger scales.

This paper examines the global distribution of electron density irregularities with scales of the order of several tens to hundreds of meters in the ionosphere by using topside sounder data from the COSMOS-1809 satellite obtained in May–June and December 1987. The diffuse traces of Z-waves on topside ionograms in a frequency band just below the upper hybrid resonance are used for diagnostics. These traces are attributed to the scattering of sounder-generated ordinary and slow extraordinary mode waves.