Photometric and in situ study of Stable Auroral Red Arc

A history of the study of Stable Auroral Red Arc (SAR arc) is presented. A compilation of SAR arc occurrences between 1967 and 1984 (including the period of the International Magnetospheric Study) reveals 383 features that are interpreted to be SAR arcs; a listing is presented. A strong correlation of SAR arc occurrence frequency with the solar cycle is demonstrated, though with a two to three year phase lag. The large number of events available to this study has confirmed the direct association of SAR arc occurrences with enhanced ring current fluxes. Clear evidence has demonstrated the consistent presence of precipitating low energy electrons into SAR arc locations identified by the Battelle operated MASP network. A search for electric currents resulting from this precipitation revealed no magnetic field fluctuations as expected to be associated with these fluxes. For the first time, atmospheric composition within SAR arcs is reported. Although there is evidence of significant compositional perturbation, the region over which this occurs is found to be considerably more extensive than the SAR arc itself. Auroral precipitation may be the primary cause of this perturbation