Calculation of Altitude Profiles of the Ionospheric Electron Density Based on the Ionograms Obtained onboard the “Mir” Space Station

We present the results of calculating the altitude profiles of the electron density below and above the ionospheric maximum using the ionosonde data obtained by the Mir space station orbited at altitudes about 350 km. It is pointed out that the data by ground-based ionosondes impede correct determination of the altitude of the nighttime ionospheric maximum.     

The Features of Ionospheric Radio Sounding Performed using the “Mir” Space Station

We present the results of numerical simulations of ionospheric parameters, which permit one to explain the occurrence of additional features in the ionograms obtained in the experiment onboard the Mir space station. During this experiment, the station flew below the electron-density maximum of the ionospheric F₂ layer. It is shown that the lower traces of the ionograms can be evidence of the presence of a horizontal gradient in the ionospheric parameters.     

Retarded lower trace on satellite ionograms as new means for studies of the ionospheric macro-irregularities

Experimental data on radio sounding of the ionosphere from satellites at heights below its main maximum are presented. In these data, additional retarded lower trace (RLT) is observed in the ionograms. It is interpreted as a trace of a probing radio signal reflected obliquely from the Earth and coming back to the satellite after refraction by sharp horizontal ionospheric irregularities. Horizontal and vertical cuts of these irregularities as well as the electron-density gradients at their side walls are determined using quantitative methods. Two sequences of ionograms for two adjacent orbits of a satellite are presented and processed for which the critical-frequency maps corrected according to the experiment are constructed. The method of weighted interpolation of approximated values at the adjacent points is used. The horizontal size of the retrieved macro-irregularity and the velocity of its motion above the Earth’s surface are obtained. A conclusion is drawn that RLT ionograms allow one to diagnose additional parameters of the ionosphere. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 1, pp. 9–20, January 2006.