The solar terrestrial event of 14-21 December 1971: The pattern of 6300 Å emission over the polar cap
Abstract
An exceptional solar terrestrial event was initiated by the ejection of plasma from the Sun on 14 December 1971 and was followed by a spectacular pattern of soft particle precipitation into the polar cap, which evolved in a slowly changing sequence until 21 December. The storm was characterized by high proton fluxes in space and near the Earth, an extended interval of northward Bz, a highly developed ring current and widespread polar cap particle fluxes. These varied from a dayside "butterfly pattern" early in the event, to highly structured Sun-aligned polar cap patterns late in recovery. A number of polar cap ground-based measurements were compiled and are reported upon. The storm seems reminiscent of the great red auroras of the IGY and some common features are noted. The 6300 Å emission is shown to result largely from direct excitation by low energy electrons, of a few hundred eV. Since the emission covered the Earth's high-latitude dayside region nearly to the invariant pole it indicates a magnetospheric topology that permits entry of low energy plasma over this region or of mechanisms which allow the generation or penetration of the plasma.
- Publication:
-
Planetary and Space Science
- Pub Date:
- July 1979
- DOI:
- 10.1016/0032-0633(79)90028-X
- Bibcode:
- 1979P&SS...27..973B
- Keywords:
-
- Auroral Irradiation;
- Oxygen Afterglow;
- Polar Caps;
- Proton Precipitation;
- Red Arcs;
- Solar Terrestrial Interactions;
- Sudden Storm Commencements;
- All Sky Photography;
- Electron Flux Density;
- Proton Flux Density;
- Solar Protons;
- Spectral Emission;
- Geophysics