The Study of Main Ionospheric Trough from Multi-station Observations

This paper presents the principal characteristics of main ionospheric trough with analysis of observational data from four ionosonde stations located between invariant latitudes A = 46-70°S. The results show following properties of main ionospheric trough: (1) the trough manifests one-self mostly in winter night; (2) the trough has two features: low electron density and large virtual height, (3) the characteristics of equatorial edge and poleward edge of trough are different; (4) the trough is in unceasing motions and variations during night.