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

During periods of intense geomagnetic activity, the high-latitude
region of our planet’s geospace environment undergoes strong particle precipitation and develops intense
electric fields. Ionization due to
particle precipitation causes a large part of
the high-latitude plasma. Electric fields mapped down magnetic field
lines from the magnetosphere to the E-region ionosphere (at 90-130 km altitude) create strong currents called
electrojets and 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 almost
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.

Work is supported by NASA LWS Grant No. 80NSSC19K0080.