Correlated dynamical changes in the near‐Earth and distant magnetotail regions: ISEE 3

Abstract

During October 1982 and January–March 1983, ISEE 3 made its first traversals of the distant (r = 60–220 RE) geomagnetic tail. Throughout this period the Los Alamos ISEE 3 plasma electron instrument detected the tailward magnetosheath, magnetopause, plasma sheet, and tail lobes. For the entire tail traversal period, nearly continuous concurrent data were available from Los Alamos charged‐particle analyzer instruments on board the spacecraft 1977‐007, 1981‐025, and 1982‐019 at geostationary orbit (6.6 RE). Using these geostationary orbit data in the local midnight sector, numerous substorm particle injection events were detected, allowing substorm onset determinations to accuracies of a few minutes. Remarkably high degrees of correlation between near‐earth substorm events and ISEE 3 transitions from one magnetotail plasma regime to another were often found throughout the tail crossing. Particularly notable were periods of “taillike” magnetic field stretching at 6.6 RE (substorm growth phases) and diametrical expansions of the distant tail seen by ISEE 3. Similarly, substorm expansion onsets seen at 6.6 RE were followed by rapid apparent contractions of the translunar tail which took ISEE 3 into magnetosheath and/or boundary layer plasmas. At ISEE 3 distances beyond ∼200 RE it is commonly observed that substorm particle injection events at 6.6 RE precede the occurrence of strong tailward plasma flow by ∼25±5 min. These results suggest a close relationship between processes in the near‐earth plasma sheet and the distant tail during substorms, with particular support for the flaring tail model of the substorm growth phase and for substorm initiation in the near‐earth magnetotail region.