Generation mechanisms for magnetosphere-ionosphere current systems deduced from a three-dimensional MHD simulation of the solar wind-magnetosphere-ionosphere coupling processes
- Communications Research Laboratory, Tokyo (Japan)
Mechanisms that generate the field-aligned current (FAC) systems in the magnetosphere-ionosphere coupling scheme by virtue of the solar wind-magnetosphere interaction are investigated with a three-dimensional magnetohydrodynamic (MHD) simulation. As a simulation scheme, the finite volume total variation diminishing (TVD) scheme on an unstructured grid system is employed for precise calculations of the ionospheric region. In the ionosphere, the divergence of the Pederson and Hall currents is matched with FAC, mainly assuming uniform conductivity. The present calculation reproduces the traditional region 1 and 2 currents in the polar ionosphere, for both the northward and southward interplanetary magnetic fields (IMFs). The calculated magnitude of the region 1 current becomes large on the dayside, in agreement with observational results. For the northward IMF, NBZ currents that dominate the entire polar cap are obtained, with a maximum on the dayside. This current is totally absent in the southward IMF result. Corresponding to the FACs, the northward IMF results in multicell convection in the polar ionosphere, and the southward IMF results in two-cell convection. On the evening side, the calculated region 1 currents flow almost along the field lines away from the Earth toward the magnetospheric low-latitude boundary layer (LLBL), then flow up the magnetopause across the field lines to high latitudes.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 117678
- Journal Information:
- Journal of Geophysical Research, Vol. 100, Issue A7; Other Information: PBD: Jul 1995
- Country of Publication:
- United States
- Language:
- English
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