A wave model interpretation of the evolution of rotational discontinuities

Journal Article · Mon Feb 01 04:00:00 EST 1993 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/92JA02364· OSTI ID:6820834

Vasquez, B J; Cargill, P J ^[1]

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1. Univ. of Maryland, College Park (United States)

The evolution of rotational discontinuities (RDs) is followed using a hybrid numerical code. An extensive parameter variation is carried out, with particular emphasis on [beta], T[sub i]/T[sub e], [theta][sub B] (the angle between the normal and total magnetic field), and the helicity of the RD. The RD structure is shown to have features in common with the evolution of both strongly modulated, nonlinear wave packets and linear dispersive wave propagation in oblique magnetic fields. For small [theta][sub B], the RD disperses linearly giving fast and Alfven waves upstream and downstream, respectively, and the familiar S-shaped hodograms. At larger [theta][sub B]([approx] 300), nonlinearity becomes important and strong coupling to a compressional (sonic) component can occur in the main current layer. When the ions am cold, there is a critical value of [beta][sub e] (= [beta][sub *]) when the intermediate wave train moves from the downstream side of the RD to the upstream and is replaced on the downstream side by slow modes. This is reflected in the hodograms by a change of the wave polarization on both sides, and represents an important modification to the original Goodrich and Cargill (1991) wave model of RDs. As T[sub i]/T[sub e] increases, the spreading rate of the current layer increases for moderate [theta][sub B]. For large [theta][sub B]([approximately]60[degrees]), RDs with electron (ion) sense of rotation show increased (decreased) spreading with increasing T[sub i]/T[sub e]. These results are applied to RDs observed in the solar wind and at the magnetopause. 49 refs., 12 figs., 3 tabs.

• OSTI ID: 6820834
• Journal Information: Journal of Geophysical Research; (United States), Journal Name: Journal of Geophysical Research; (United States) Vol. 98:A2; ISSN JGREA2; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

661320* -- Auroral
Ionospheric
& Magnetospheric Phenomena-- (1992-)
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ALFVEN WAVES
CHARGED PARTICLES
COUPLING
HYDROMAGNETIC WAVES
IONS
MAGNETIC FIELDS
MAGNETOPAUSE
MOTION
PLASMA WAVES
POLARIZATION
ROTATION
SOLAR ACTIVITY
SOLAR WIND
WAVE PACKETS
WAVE PROPAGATION