Density Troughs in the Ionosphere Sustained by Transport Barriers

Abstract

This study explores the relaxation and sustainability of density irregularities and plasma flows in the Earth's ionosphere. To do this, we use a modified model of drift-wave turbulence known as the Hasegawa-Wakatani model. Similar to turbulent processes in laboratory plasmas, we explore a powerful mechanism that can reduce the turbulent plasma transport. This mechanism is associated with the creation of “zonal flows,” cutting across the gradients of particle density and magnetic fields. They work effectively to minimize particles' random movement and reduce the turbulence causing this movement. The zonal flows create transport barriers in areas where the density gradient is steepest and where drift waves grow most vigorously. The transport barriers significantly delay the refill of low-density regions with surrounding plasma. They also lead to changes in the electric potential of the plasma and influence the movement of ions in the direction of the magnetic field. Our research investigates how these zonal flows are generated and how effectively they sustain density irregularities. We also examine the spectral characteristics of turbulence in and around these barriers.