Signature of transient boundary layer processes observed with Viking

Journal Article · Sat Feb 01 04:00:00 EST 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/91JA02490· OSTI ID:5305576

Woch, J; Lundin, R ^[1]

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1. Swedish Inst. of Space Physics, Kiruna (Sweden)

Transient penetration of plasma with magnetosheath origin is frequently observed with the hot plasma experiment on board the Viking satellite at auroral latitudes in the dayside magnetosphere. The injected magnetosheath ions exhibit a characteristic pitch angle/energy dispersion pattern earlier reported for solar wind ions accessing the magnetosphere in the cusp regions. In contrast to the continuous plasma entry in the cusp, the events discussed here show temporal features which suggest a connection to transient processes at or in the vicinity of the magnetospheric boundary. A single event study confirms previously published observations that the injected ions flow essentially tailward with a velocity comparable to the magnetosheath flow and that the energy spectra inferred for the source population resemble magnetosheath spectra. Based on a statistical study, it is found that these events are predominantly observed around 0800 and 1600 MLT, in a region populated by both rung current/plasma sheet particles and by particles whose source is the magnetosheath plasma. Magnetic field line tracing based on the Tsyganenko magnetic field model yields a scatter of the source locations around the mid-latitude region of the magnetospheric boundary. The probability for these events to occur is highest when the interplanetary magnetic field (IMF) is confined to the ecliptic plane. The connection of the events to transient impulsive solar wind/magnetosphere interaction processes, such as transient reconnection (FTE), impulsive plasma transfer, Kelvin Helmholtz instabilities, and solar wind pressure pulses, is discussed. A relation with transient reconnection can be excluded.

• OSTI ID: 5305576
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A2; ISSN 0148-0227; ISSN JGREA
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
AURORAL ZONES
BARYONS
BOUNDARY LAYERS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
ELEMENTARY PARTICLES
ENERGY SPECTRA
FERMIONS
HADRONS
HELMHOLTZ INSTABILITY
INSTABILITY
INTERACTIONS
INTERPLANETARY MAGNETIC FIELDS
ION DRIFT
IONIC COMPOSITION
LAYERS
MAGNETIC FIELDS
MAGNETIC RECONNECTION
MAGNETOSHEATH
NUCLEONS
ORIGIN
PLASMA DENSITY
PLASMA DRIFT
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
POLAR CUSP
PROTONS
SATELLITES
SOLAR ACTIVITY
SOLAR WIND
SPECTRA
TRANSIENTS