The dynamics of the auroral oval and ionospheric trough boundaries according to data from the DMSP satellites and ground-based ionosonde network

This paper presents the results of a combined analysis of the experimental data of vertical- and oblique-incidence ionospheric sounding in the northeastern region of Russia and of the DMSP satellite data from 1999 to 2003. During geomagnetic disturbances period on ionograms we can see anomalous diffuse signals, which propagates outside great circle arc. The joint data analysis permits to suggest that the appearance of additional anomalous signals is connected with radio waves refraction in auroral oval and main ionospheric trough areas and with scattering on small-scale field-aligned irregularities close to auroral oval equatorial boundary in the region of electron diffuse precipitation. The basic attention is given to diagnostics of main ionospheric trough boundary and auroral oval zones position during geomagnetic disturbances periods.