Formation of the Harang reversal and its dependence on plasma sheet conditions: Rice convection model simulations
Article first published online: 2 JUL 2009
Copyright 2009 by the American Geophysical Union.
Journal of Geophysical Research: Space Physics (1978–2012)
Volume 114, Issue A7, July 2009
How to Cite
2009), Formation of the Harang reversal and its dependence on plasma sheet conditions: Rice convection model simulations, J. Geophys. Res., 114, A07204, doi:10.1029/2008JA013955., , , and (
- Issue published online: 2 JUL 2009
- Article first published online: 2 JUL 2009
- Manuscript Accepted: 19 MAR 2009
- Manuscript Revised: 3 FEB 2009
- Manuscript Received: 29 NOV 2008
- Harang reversal;
- field-aligned currents
 The goal of this paper is to understand the formation of the Harang reversal and its association with the region 2 field-aligned current (FAC) system, which couples the plasma sheet transport to the ionosphere. We have run simulations with the Rice convection model (RCM) using the Tsyganenko 96 magnetic field model and realistic plasma sheet particle boundary conditions on the basis of Geotail observations. Our results show that the existence of an overlap in magnetic local time (MLT) of the region 2 upward and downward FAC is necessary for the formation of the Harang reversal. In the overlap region the downward FAC, which is located at lower latitudes, is associated with low-energy ions that penetrate closer to Earth toward the dawn side, while the upward FAC, which is located at higher latitudes, is associated with high-energy ions. Under the same enhanced convection we compare the Harang reversal resulting from a hotter and more tenuous plasma sheet with the one resulting from a colder and denser plasma sheet. For the former case the shielding of the convection electric field is less efficient than for the latter case, allowing low-energy protons to penetrate further earthward, resulting in a Harang reversal that extends to lower latitudes, expands wider in MLT, and is located further equatorward than the upward FAC peak and the conductivity peak. The return flows of the Harang reversal in the hot and tenuous case are located in a low conductivity region. This leads to an enhancement of these westward flows, resulting in subauroral polarization streams (SAPS).