Next Generation of Magnetosphere-Ionosphere-Thermosphere Coupling Models
P. Song1, V. M. Vasyliūnas1,2 and J.-N. Tu1
1. Center for Atmospheric Research and Department of Environmental, Earth & Atmospheric
Sciences, University of Massachusetts Lowell,
2. Max-Planck-Institut für Sonnensystemforschung, 37191 Katlenburg-Lindau, Germany.
Abstract.
Over the past decades, countless studies have been dedicated to describing the magnetosphereionosphere/thermosphere coupling and the influences of the magnetospheric variations on the
ionosphere/thermosphere system. The models that have been used for practical purposes in
global sense are with either a static ionosphere or a height-integrated ionosphere, both of which
are not valid or adequate to describe the transient ionospheric processes such as substorms or
auroral brightenings. A framework of theory has been proposed and is being developed to selfconsistently describe an electromagnetically coupled collisional plasma-neutral system with the
inductive and plasma as well as neutral dynamic effects. In this presentation, we describe the
new approach of multi-fluid inductive dynamic magnetosphere-ionosphere-thermosphere (MIDMIT) coupling, in which ions and neutrals are treated dynamically as multiple fluids. The
magnetic field can vary with time and in space: its temporal variations induce electric field and
its spatial variations produce currents. The conventional concepts of mapping the electric
potential, magnetic field, and field-aligned currents become invalid during the dynamic stage.
We compare the differences between this inductive-dynamic theory and the conventional
magnetosphere-ionosphere/thermosphere coupling mechanisms. The inductive-dynamic theory
shows that the transition for the ionosphere to respond to a magnetospheric change lasts for
about 20-30 min, the critical time scale for most of ionospheric dynamic processes. During the
transition period, large-amplitude fluctuations and enhanced heating are expected.