[en] Variations of electron density and electron temperature in the subauroral ionosphere during the magnetospheric storm on April 3-4, 1979 are analyzed according to the data of the ''Interkosmos-19'' satellite. The sharpest displacement of a middle latitude fall-through to the equator is primarily caused by the turn-over of Bsub(z)-component of the interplanetary magnetic field (IMF) to the South. This displacement has taken place immediately after the turn-over of IMF Bsub(z)-component to the South in the day-time with a approximately 2 h delay in the night-time. and a approximately 40 min delay in around midnight. The general amplitude of fall-trhrough displacement is approximately 18. 20 and 17 deg for the day- and night-time and around midnight. The minimum latitude of the fall-through equals 56, 48 and 43 deg in the day- and night-time and midnight respectively. The saturation in IMF equatorial displacement is observed in the dark time of the day near the maximum of IMF Bsub(z)-component and Ksub(p) index

[en] Presented are the results of measurements along the ''Interkosmos 19'' artificial satellite of the electron concentration and its vicinity and in the F2 layer maximum. The cycle variations of electron concentration at these levels and horizontal gradients of these frequencies are evaluated. It is shown that electron concentration changes at the height of 900-1000 km appeared more significant than in the maximum of the F2 layer. The electron concentration in the region of equatorial latitudes has increased from the minimum of solar activity up to its maximum by more than 10 times

[en] The most characteristic types of f₀F₂ latitudinal profiles in the night subauroral ionosphere in years of maximum solar activity are selected according to the data of coordinated measurements, conducted at the Interkosmos-19 satellite and at vertical sounding ground stations in the north hemisphere 20-70deg E sector. Data on structure of the main ionospheric through separate types are presented, empirical formula of dependence of the main ionospheric through polar wall invariant latitude on local time and geomagnetic activity is obtained