Zonal flows and magnetic fields driven by large‐amplitude Rossby‐Alfvén‐Khantadze waves in the E‐layer ionosphere

Abstract

AbstractPlanetary‐scale waves and vortices in the weakly ionized ionospheric E layer are dominated by the Hall conductivity that couples the Rossby and Alfvén dynamics giving rise to what are called Rossby‐Alfvén‐Khantadze electromagnetic structures. At finite amplitudes we show that the nonlinearities in the dynamics generate sheared zonal‐flow velocities and zonal magnetic field fluctuations. The zonal‐flow mechanism is based on the parametric excitation of the zonal variations through three‐wave mode coupling in the planetary‐scale waves. The coupled dynamics of the nonlinear 3‐D incompressible flows and the magnetic field fluctuations are derived and used to derive the structure and growth rates for the zonal flows and zonal magnetic fields. Large‐amplitude planetary waves are shown to drive up magnetic fluctuations up to 100 nT.