The Ring Current as Expansion of the Ionosphere
Abstract
Solar wind energy dissipated in the auroral ionosphere produces expansion of ionospheric plasmas, creating an auroral wind and a cloud of heavy ion plasma whose upper boundary moves upward through the magnetosphere with increasing energy inputs. This boundary is essentially that between dynamo plasmas ( J·E < 0) and load plasmas (J·E > 0). As the ring current magnitude increases during storm times, the heavy ion component increases exponentially, while the light ion component increases slowly by comparison. Thus, increasingly with the magnitude of geospace storms, the ionosphere expands to fill the inner magnetosphere and near-Earth plasma sheet. The solar wind energy dissipated within this expanding plasma raises the heavy ion plasma pressure and inflates the magnetosphere correspondingly. Using published empirical data, we introduce auroral wind test particle outflows into a global simulation to assess the impact, and find that substantial pressures of ionospheric particles are formed. Thus, we can understand geospace storms as the result of enhanced solar wind energy dissipation in the ionosphere, causing it to expand with sufficient pressure to inflate the magnetosphere, producing the ring current. We conclude that global simulation models will need to incorporate ionospheric plasma pressure to accurately describe and predict the storm time ring current behavior.
- Publication:
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AGU Spring Meeting Abstracts
- Pub Date:
- May 2006
- Bibcode:
- 2006AGUSMSM51A..04M
- Keywords:
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- 2431 Ionosphere/magnetosphere interactions (2736);
- 2736 Magnetosphere/ionosphere interactions (2431);
- 2778 Ring current