Growth of Auroral Structures, Vortex Formation, Turbulence Transition, and Energy Cascade in Alfvénic Magnetosphere‐Ionosphere Coupling

Abstract Magnetohydrodynamic simulations of the Alfvénic magnetosphere‐ionosphere (M‐I) coupling reveal a comprehensive picture of nonlinear development of the feedback instability, demonstrating spontaneous growth of auroral structures of density and current enhancements, vortex formation, turbulence transition, and energy cascade. Turbulent energy spectra consistent with the ‐law and the critical balance are self‐organized in the feedback M‐I coupling with ionospheric density change. Simultaneously, field‐aligned current and vorticity fluctuations in the auroral ionosphere show different power laws in consistent with observations. The growth of feedback instability and the turbulent energy cascade transfer the kinetic and magnetic energy from a large magnetospheric convection scale to a small dissipation scale.