Electromagnetic waves in the auroral and subauroral regions of the topside ionosphere

Abstract

The density and temperature of the plasma electron component and wave emission intensity in the topside ionosphere were measured by the INTERCOSMOS-19 satellite. In the subauroral ionosphere, a decrease in the plasma density correlates with an increase in the plasma electron component temperature. In this case, the additional increase in the electron component temperature was measured in regions with increased plasma density gradients during the substorm recovery phase. In a linear approximation, the electromagnetic wave growth increments are small on electron fluxes precipitating in the auroral zone. It has been indicated that Bernstein electromagnetic waves propagating in the subauroral topside ionosphere can intensify in regions with increased plasma density gradients on electron fluxes orthogonal to the geomagnetic field, which are formed when plasma is heated by decaying electrostatic oscillations of the plasma electron component. This can be one of the most important factors responsible for the intensification of auroral kilometric radiation.