On the possibility of using an electromagnetic ionosphere in global MHD simulations
Global magnetohydrodynamic (MHD) simulations of the Earth's magnetosphere must be coupled with a dynamical ionospheric module in order to give realistic results. The usual approach is to compute the field-aligned current (FAC) from the magnetospheric MHD variables at the ionospheric boundar...
| Main Author: | |
|---|---|
| Format: | Article |
| Language: | English |
| Published: |
Copernicus Publications
1998-04-01
|
| Series: | Annales Geophysicae |
| Online Access: | https://www.ann-geophys.net/16/397/1998/angeo-16-397-1998.pdf |
| Summary: | Global magnetohydrodynamic (MHD) simulations
of the Earth's magnetosphere must be coupled with a dynamical ionospheric module
in order to give realistic results. The usual approach is to compute the
field-aligned current (FAC) from the magnetospheric MHD variables at the
ionospheric boundary. The ionospheric potential is solved from an elliptic
equation using the FAC as a source term. The plasma velocity at the boundary is
the <b>E</b> × <b>B</b> velocity associated with the ionospheric potential.
Contemporary global MHD simulations which include a serious ionospheric model
use this method, which we call the electrostatic approach in this paper. We
study the possibility of reversing the flow of information through the
ionosphere: the magnetosphere gives the electric field to the ionosphere. The
field is not necessarily electrostatic, thus we will call this scheme
electromagnetic. The electric field determines the horizontal ionospheric
current. The divergence of the horizontal current gives the FAC, which is used
as a boundary condition for MHD equations. We derive the necessary formulas and
discuss the validity of the approximations necessarily involved. It is concluded
that the electromagnetic ionosphere-magnetosphere coupling scheme is a serious
candidate for future global MHD simulators, although a few problem areas still
remain. At minimum, it should be investigated further to discover whether there
are any differences in the simulation using the electrostatic or the
electromagnetic ionospheric coupling.<br><br><b>Key words.</b> Ionosphere · Ionosphere-magnetosphere
interaction · Magnetospheric physics · Magnetosphere-ionosphere interaction ·
Space plasma physics · Numerical simulation studies |
|---|---|
| ISSN: | 0992-7689 1432-0576 |