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1. Ionospheric Alfven Resonator

The model of ionospheric Alfven resonator with the mechanism of the feedback instability is developped which allows to explain the main features of ionosphere-magnetosphere interactions. For the first time it became possible to explains the effect of suppression of the discrete aurora by solar ultraviolet radiation which was observed on board the American weather DMSP-satellite. The model developed included the effect of coupling of the shear Alfven waves to the fast compressional waves through the ionospheric boundary conditions. This effect results in the appearance of the Hall dispersion and subsequent shift of the Ionospheric Alfven Resonator frequency spectrum. The excitation mechanism connected with Alfven Resonator interaction with the magnetospheric convective flow is considered.

The effect of the ionosphere on the formation of IPDP and Pc1 (“pearl”) pulsations spectrum was investigated. On December 15,1984, a series of Pc1 pearls was observed by The Finnish network, which subsequently increased in frequency and developed to a IPDP after substorm onset. The EISCAT radar was simultaneously monitoring the mid- to high-latitude ionosphere. It has been calculated the ionospheric resonator properties during the different phases of the event using EISCAT observations. Contrary to earlier results, we found that the Pc1/IPDP wave frequency on ground corresponds to the maximum of the transmission coefficient and the minimum of the reflection coefficient. The properties of the ionospheric resonator could be modified so as to allow the observed increase in wave frequency. It has been proposed a new model for IPDP formation, whereby the ionosphere acts as an active agent in forming the IPDP signal on the ground.

2. Effect of the ponderomotive forces, induced by the geomagnetic pulsations.

By using a general expression for the ponderomotive wave force, it has been evaluated the action of ion cyclotron Alfven waves on the plasma density in the longitudinal waveguide. The main effect is the condensation of the plasma in the vicinity of the waveguide equator. It was shown that the existence of so-called “magnetic holes” (magnetic field minima) along the field lines play a significant role in the plasma pressure balance in the Earth’s magnetosphere. Ponderomotive forces induced by the Pc1 geomagnetic pulsations propagating through these regions can lead to a significant plasma accumulation there.

It is suggested that the existence of regions with decreasing magnetic fields at high-altitude field lines can lead to resonance absorption of ioncyclotron waves (the “magnetic beach”effect).

3. Inertio-Gravity and Rossby-Type Waves in Self-Gravitating Systems.

A dispersion relation is derived for the azimuthal propagation of inertio-gravity and gravitational Rossby waves in a nonuniform self-gravitating system. The instability condition for the azimuthally propagating perturbations and its possible application to the formation of galaxy disk spirals is discussed. In the region where the system is stable, the nonlinear coupling between inertio-gravity and gravitational Rossby waves is considered, accounting for the action of the low frequency force associated with the inertio-gravity waves. It is shown that this interaction is governed by a pair of equations, which can be useful for studying the modulational instability of a constant amplitude inertio-gravity waves as well as the dynamics of nonlinearly coupled inertio-gravity and gravitating Rossby waves.