Coupled Feedback Mechanisms in the Magnetosphere-Ionosphere System

The dynamics of the inner-magnetosphere and ionosphere are coupled through complex feedback mechanisms involving waves, DC electric fields, particle flows, and field aligned currents. A full understanding of the behavior of either the magnetosphere or ionosphere requires an account of the other. As a generic example, the DC electric field associated with advection in the inner-magnetosphere maps along magnetic field lines into the ionosphere where the resulting ExB drifts can modify the plasma density altitude profile and recombination rates, altering conductivity. The consequential change in ionospheric conductivity, along with the closure of field aligned currents, also associated with advection, can modify the magnetospheric DC electric field (as is thought to occur in subauroral polarization streams), which in turn can alter the particle drifts and particle energization in the inner-magnetosphere. Since wave-particle interactions are sensitive to the particle energy and pitch angle distributions, such processes can then give rise to wave generation and/or particle energization and/or loss. Precipitation of particles can further modify the ionospheric conductivity. Thus, all of the above-mentioned phenomena and processes may constitute components of a closely linked system that do not, in isolation, fully describe the system dynamics. Other processes that persist during geomagnetically quiet times, such as plasmasphere refilling and its reverse, the down-flow of the relatively cool plasmaspheric plasma into the topside ionosphere, also play an important role in magnetosphere-ionosphere (M-I) coupling.

The aim of this Research Topic is to collect a wide variety of studies that contribute to understanding the magnetosphere-ionosphere as a coupled feedback system. This Research Topic solicits contributions from researchers involved in inner-magnetosphere, ionosphere, and the coupling between these systems, approached from either satellite or ground-based data sets, theory, modeling, simulations, or studies involving machine learning.

In particular we welcome contributions across a variety of subtopics related to magnetosphere-ionosphere coupling, including works targeting:
• advection/convection in the inner-magnetosphere and ionosphere;
• meso-scale convective subauroral phenomenona, including STEVE, subauroral polarization streams (SAPS), subauroral ion drifts (SAIDS);
• SAR arcs, diffuse electron and proton aurora, discrete aurora;
• ring current ions and electrons, and injected plasma sheet particles;
• shielding of the inner-magnetosphere;
• field aligned currents;
• wave propagation between magnetosphere and ionosphere;
• ionospheric plasma outflows and upwelling;
• magnetospheric particle precipitation into the ionosphere;
• plasmasphere erosion, refilling, and the ionospheric footprint of the plasmasphere (e.g. trough, SED, plume, etc.);
• hemispheric asymmetries in the ionosphere, their causes and impact on the magnetosphere;
• wave-particle or wave-plasma interactions in the inner-magnetosphere, in particular those associated with precipitation and modification of ionospheric conductance;
• Poynting flux associated with steady convection, MHD waves, kinetic and inertial Alfvén waves, and the transport of energy into and out from the ionosphere.

Research Topic image details: STEVE observed in Ontario, Canada. Credit: Lauri Kangas (http://photon-echoes.com/index.html)