Kelvin-Helmholtz instability at the magnetospheric boundary: Dependence on the magnetosheath sonic Mach number

Journal Article · Wed Jul 01 00:00:00 EDT 1992 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA00791· OSTI ID:7012637

Miura, Akira ^[1]

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1. Univ. of Tokyo (Japan)

It has recently been demonstrated, by means of a two-dimensional MHD simulation, that a finite thick velocity shear layer with super-Alfvenic velocity jump at the magnetospheric boundary is unstable to the Kelvin-Helmholtz (K-H) instability no matter how large the magnetosheath sonic Mach number (M{sub s}); a result suggesting that the tail flank boundary of the magnetosphere is unstable to the K-H instability. In order to investigate this consequence further, the dependence of the development of the K-H instability of M{sub s} is studied in detail. For all magnetosheath sonic Mach numbers a velocity boundary layer is formed by the instability inside of the magnetopause, and it becomes wider for a smaller magnetosheath sonic Mach number. A flow vortex is excited at the inner edge of the velocity boundary layer of all sonic Mach numbers, and the magnetopause boundary is more highly nonlinearly corrugated by the instability for a smaller sonic Mach number. The net energy and momentum flux densities into the magnetosphere are calculated just prior to the saturation stage. The anomalous viscosity by the instability decreases in the absolute magnitude with increasing M{sub s}; result suggests that the dayside (except the subsolar region) and the dawn-dusk magnetopauses, where the magnetosheath flow remains subsonic, are the most viscous parts of the boundary, although the tail flanks are also found to be viscous enough for the viscous interaction.

• OSTI ID: 7012637
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 97:A7; 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
BOUNDARY LAYERS
EARTH ATMOSPHERE
EARTH MAGNETOSPHERE
HELMHOLTZ INSTABILITY
HYDROMAGNETIC WAVES
INSTABILITY
INTERACTIONS
LAYERS
MACH NUMBER
MAGNETOSHEATH
PLASMA INSTABILITY
PLASMA MACROINSTABILITIES
SHEAR
SHOCK WAVES
SOLAR ACTIVITY
SOLAR WIND
VELOCITY
VORTICES