Theoretical models of localized electrostatic structures in the auroral magnetosphere

A 3D fully nonlinear theory of ion acoustic solitary structures is constructed in three-component plasma consisting of non-thermal electrons, a hot ion background and a cold ion beam. The theory is based on the derivation of a modified Korteweg-de Vries-Zakharov-Kuznetzov (KdV-ZK) equation. The ion motion is treated in the MHD approximation with self-consistent distributions and dynamics of all plasma components. Some numerical examples are presented for plasma conditions pertinent to the subauroral magnetosphere and outer plasmasphere in the stage of refilling after a magnetic storm.