## ULF waves in the Magnetosphere-Ionosphere Coupling

**Abstract:** Ultra-Low Frequency (ULF) Alfvén waves carry significant fluxes of electromagnetic power along auroral magnetic field lines and play a major role in the redistribution of electromagnetic power, particle density, energy, mass, and momentum between the ionosphere and magnetosphere at high latitudes. A particularly important feature of these waves is their casual connection with discreet auroral arcs. The 2D magnetohydrodynamic (MHD) models, used currently to describe these waves’ origination and interaction with the ionosphere and magnetosphere (MI), are limited by the axisymmetric geometry and linear approach. I currently investigate nonlinear, 3D electromagnetic coupling between the ionosphere and the magnetosphere at high latitudes. My study is based on a comprehensive, nonlinear, 3D and time-dependent numerical model describing dynamics of ULF Alfvén waves in the magnetosphere and the active electromagnetic coupling between these waves and the ionospheric plasma. This model is used to investigate the nonlinear spatiotemporal properties and dynamics of ULF waves and magnetic field-aligned currents at high altitudes and to model observational events selected from the ground instruments, satellites and sounding rockets.