MIR space station topside sounding near Taiwan

First results from ionospheric topside sounding data received at Taiwan National Central University are reported. The sounding was accomplished from the topside sounder on the Russian MIR. The topside ionograms and calculated vertical profiles of electron concentration were compared with corresponding bottomside ionograms and profiles. The total composed vertical profiles were obtained. A very good correspondence between the topside and bottomside ionospheric data, both for critical frequency and peak height was achieved and a total composite vertical profile was thus obtained. The scaled local plasma (ordinary cutoff) and critical frequencies, as well as topside profiles along the station pass, permit the position and shape of the northern crest of the equatorial anomaly to be determined. The low orbit of MIR space station gives the unique possibility to check the peak height models of the ionosphere due to ability of in-situ and remote sounding measurements simultaneously, especially in periods when the station is inside the peak.