MIR Space Station Topside Sounding near Taiwan

Sergei A Pulinets,Nikolai P Danilkin,Yu-Jung Chuo,Jann-Yenq Liu,Nadezhda G Kotonaeva,Depuev Victor Kh

doi:10.3319/tao.2001.12.3.525(a)

Abstract

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.

Highlights

The equatorial anomaly is one of the most dynamic and unpredictable regions of the Earth's ionosphere
The MIR station gives the perfect opportunity to check the validity of the topside profiles calculation algorithm because of two factors: a) low altitude of the MIR station orbit makes the profiles short and calculations more precise, b) again due to the low altitude sometimes the station will fall directly into the peak of electron concentration, the peak height and peak electron density could be determined from the in situ measurements
The present paper demonstrates the capabilities abilities of the ionospheric sounding from low orbiting platforms. This kind of sounding is especially interesting when the station orbit altitude is in the vicinity of the peak height of the Earth's ionosphere to show what happens in the region of equatorial anomaly

Summary

INTRODUCTION

The equatorial anomaly is one of the most dynamic and unpredictable regions of the Earth's ionosphere. TAO, Vol 12, No 3, September 2001 content but not on the structure of the equatorial anomaly, including plasma irregularities of different scales which have a major effect on radiowave propagation. The Alouette 1 and 2, ISIS 1 and 2, Intercosmos, ISS-B and COSMOS 1809 have proved their effectiveness for global ionosphere monitor ing possibilities (Pulinets and Benson 1999). The installation of the topside sounder onboard the Russian MIR space station provides a new opportunity for global studies of the Earth's ionosphere. The topside sounder onboard the MIR station is a modified replica of those installed onboard the Intercosmos-19 and COSMOS 1809 satellites described in Pulinets (1989). It offers possibility to record data for global moni toring regime or to transmit them directly to a receiving station when passing within 2500 km of the station

RECEIVING POINT AT CHUNG-LI

TOPSIDE SOUNDING BACKGROUND

TOPSIDE AND BOTTOM SIDE VERTICAL PROFILES COMPARISON

EQUATORIAL ANOMALY PARAMETERS DERIVED FROM TOPSIDE

CONCLUSION