An S3-3 satellite study of the effects of the solar cycle on the auroral acceleration process

A statistical study of the effects of the solar cycle, as indicated by the value of F10.7, has been made utilizing a data base of electrostatic shocks and the associated ion beams, ion conics, and electron distributions obtained by the S3-3 satellite during the rising phase of the solar cycle. Ion composition was not included since the ion detectors utilized for this study did not determine mass. The acceleration of ions in association with electrostatic shocks is strongly dependent on F10.7 at altitudes of ∼2000 - 8000 km. For low F10.7 (<80), ∼43% of the shocks were associated with conics and ∼43% with beams, whereas for high F10.7 (100-225), ∼18% of the shocks were associated with beams and ∼64% with conics. This difference was observed for essentially all magnetic local times and altitudes except the period from 0000 - 0600 MLT. These results suggest that parallel potential drops are less common at altitudes below 8000 km during solar maximum than during solar minimum. However, for the events where ion beams were observed, the average parallel potential drop below the satellite (as determined from the peak ion energy) had very similar values, and approximately half of the potential occurred below the satellite altitude for both high and low F10.7. The observations described herein are consistent with the increased occurrence frequency of O+ conics during high F10.7 observed by Yau et al. (1985) in the DE-1 data.