Longitudinal effect on the shape of the main ionospheric trough in the disturbed period of 20–25 October 1981

Abstract

The data of the Northern Hemisphere network of ionospheric stations ( φ L = 40–70°) have been used for the analysis of the longitudinal variations of the electron concentration at the altitude of the F2 layer maximum. The data through the period 20–25 October 1981 have been used; two large magnetic storms occurred during these days: a longitudinal effect on the trough shape has been confirmed; the effect is shown to be independent of the UT-control on the plasma ionization distribution. The use of satellite measurements (DE-B) for the same period allowed the authors to reveal a relationship between the amplitude of the longitudinal effect and the altitude. The relationship found between the sign of the magnetic declination and the shape of latitudinal profiles of the electron concentration in the trough is in good agreement with the concept of the thermospheric effect on trough formation.