Improving Conductance Modeling in Global Magnetosphere–Ionosphere–Thermosphere Simulations during Geomagnetic Storms: An Important Element of Space Weather Modeling

Abstract:

During periods of intense geomagnetic activity, the Earth’s high-latitude geospace environment develops both strong particle precipitation and intense electric fields. Ionization due to particle precipitation causes a large part of the high-latitude plasma. Electric fields generated in the magnetosphere and mapped down to the E-region ionosphere (at 90-130 km altitude) create strong currents called electrojets and these often drive plasma instabilities. These instabilities give rise to plasma turbulence that induces nonlinear particle transport and strong anomalous electron heating that elevates the temperature by up to one order of magnitude --- an effect observed by radars for forty years. All these phenomena play an important role in magnetosphere-ionosphere-thermosphere (MIT) coupling by increasing the ionospheric conductances and modifying geospace energy flows, affecting the structure of the magnetosphere. A physics-based quantitative understanding of anomalous conductance and global energy transfer is important for accurate modeling of space weather. Our recent theoretical analysis and kinetic simulations have significantly improved the description of particle precipitation and anomalous conductivity. These analyses have shown that such combined factors as multiple reflections of precipitating electrons from conjugate hemispheres and anomalous conductivity caused by E-region turbulence can increase the ionospheric conductances by a factor of four or even more. These anomalous factors need to be included in global MIT models for accurate modeling of the near-Earth environment during big geomagnetic storms or substorms.