Energetic magnetospheric ions at the dayside magnetopause: Leakage or merging

Journal Article · Sun Nov 01 04:00:00 EST 1987 · J. Geophys. Res.; (United States)

DOI:https://doi.org/10.1029/JA092iA11p12097· OSTI ID:5514190

Sibeck, D G; McEntire, R W; Lui, A T.Y.; Lopez, R E; Krimigis, S M; Decker, R B; Zanetti, L J; Potemra, T A

We elaborate upon the leakage model for the escape of energetic magnetospheric particles into the magnetosheath. Unlike the merging model, no interconnection (or merging) of magnetospheric and magnetosheath magnetic field lines is required. Because outer magnetospheric energetic particle drift paths intersect the magnetopause, the leakage model requires the continual escape of ions at postnoon local times and electrons at prenoon local times, regardless of solar wind conditions. It also predicts a division between dawnward and duskward streaming ions at the point where most magnetosheath magnetic field lines make their closest approach to the magnetopause, typically near 1500 LT. Like the merging model, the leakage model predicts equatorward streaming just inside the magnetopause. We study the motion of an escaping energetic ion at a planar magnetopause to show that, without scattering, ions must move dawnward and northward in a duskward magnetosheath magnetic field and dawnward and southward in a dawnward magnetosheath magnetic field. Scattering permits some ions to move duskward. We present new observations of streaming ions outside the dayside magnetopause made by the Charge Composition Explorer satellite, a part of the Active Magnetospheric Particle Tracer Explorers program. To place these observations in context, we have performed a statistical study of previous particle observations both inside and outside the dayside magnetopause. The ensemble of observations indicates that energetic magnetospheric ions of all species continually escape from the dayside magnetosphere and stream along magnetosheath magnetic field lines, even when no merging is expected. The magnetosheath magnetic field controls the direction in which the ions stream: they move away from the magnetosphere.

• Research Organization: The Johns Hopkins University Applied Physics Laboratory, Laurel, Maryland
• OSTI ID: 5514190
• Journal Information: J. Geophys. Res.; (United States), Journal Name: J. Geophys. Res.; (United States) Vol. 92:A11; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

640201* -- Atmospheric Physics-- Auroral
Ionospheric
& Magetospheric Phenomena
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ATOMIC IONS
CHARGED PARTICLES
EXPLORER SATELLITES
IONIC COMPOSITION
IONS
MAGNETIC FIELDS
MAGNETOPAUSE
MAGNETOSHEATH
SATELLITES