Origination of new branches of planetary electromagnetic waves in the ionosphere

Physical mechanisms of generation of new modes of large-scale electromagnetic waves in the ionosphere are proposed. Solving the set of equations of magnetic hydrodynamics of the ionosphere, it has been indicated that the geomagnetic field latitudinal inhomogeneity, which is the permanent (fundamental for global processes) factor in the Earth's ionosphere, generates an additional quasi-elastic electromagnetic force. As a result, new rapid and slow planetary electromagnetic waves are generated in the ionospheric E region, and a stationary planetary electromagnetic wave is originated along a parallel in the ionospheric F region. These stationary waves propagate along latitudinal circles in the form of advancing waves, if the predominant zonal wind is taken into account. Parameters of the considered waves have been numerically analyzed for the periods of low and high solar activity, using known models of the ionosphere and neutral atmosphere. It has been indicated that the periods, frequencies, and lengths of the considered waves, as well as the accompanying pulsations of the geomagnetic field (to ten nonoteslas), agree well with the properties and parameters of the midlatitude long-period oscillations and magneto-ionospheric wave disturbances experimentally observed in the ionosphere.