Temporal evolution of ionospheric electric field driven by field-aligned current
Abstract
Based on a simple Senior-Blanc's time-dependent model and using a step-varying field-aligned current instead of the potential as the driving force, the temporal evolution of the ionospheric electric field is discussed. It is shown that configurations in both cases are similar--the relaxation time toward the steady state is about 50 minutes in both cases. However, there are some differences between them: under current driving situations, the potential at the boundary of the polar cap is not constant but decreases exponentially toward the steady state; at the auroral zone the difference between the steady state and the initial time electric fields is very small. In addition, the steady state value of the second field-aligned current calculated from the model is even closer to the observed value. The latitudinal variation of the potential is steeper, and the maximum potential appears earlier. The calculated shielding factor and the shielding time constant show that the shielding effect under the current driving situation seems stronger than that in the potential driving case.
- Publication:
-
JPRS Report: Science and Technology. China
- Pub Date:
- June 1987
- Bibcode:
- 1987rstc.rept...24G
- Keywords:
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- Earth Ionosphere;
- Electric Current;
- Electric Fields;
- Field Aligned Currents;
- Geoelectricity;
- Temporal Distribution;
- Alignment;
- Steady State;
- Geophysics