Observations of High-Speed Plasma Flow Near the Earth's Magnetopause: Evidence for Reconnection.
Abstract
In an attempt to confirm the evidence for reconnection reported by Paschmann et al. (1979) we have examined three-dimensional plasma velocity distributions sampled near the magnetopause using the LEPEDEA plasma instrument. During the magnetopause crossing of 8 September 1978, we observe high-speed plasma flow in the magnetospheric boundary layer which is suggestive of the accelerated flow predicted by reconnection models. However, simultaneous measurements of > or = 45 keV energetic electrons show pancake-shaped pitch-angle distributions which indicate a closed field line regime where as the highspeed plasma flow is predicted to occur on open field lines for the reconnection hypothesis. Low-energy plasma and energetic ion observations do not show any evidence for a local flow component normal to the magnetopause, and the energetic particle measurements show no evidence for a finite normal magnetic field component. Since the energentic particle angular distributions indicate that the high-speed plasma flow occurs partly or entirely on closed field lines, we suggest that the simplest hypothesis is to place the entire boundary layer observed during this crossing on closed field lines. We find that several detailed features of the available measurements can be explained readily in this way. Our ISEE observations appear to be most consistent with impulsive injection of magnetosheath plasma across the magnetopause in a process that involves both MHD and plasma kinetic instabilities. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1981
- Accession Number
- ADA102760
Entities
People
- Louis A. Frank
- T. E. Eastman
Organizations
- University of Iowa