Oblique propagation of nonlinear hydromagnetic waves: One- and two-dimensional behavior

Journal Article · Wed May 01 00:00:00 EDT 1991 · Journal of Geophysical Research; (United States)

DOI:https://doi.org/10.1029/90JA01588· OSTI ID:5186759

Malara, F ^[1]; Elaoufir, J ^[2]

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1. Univ. della Calabria, Cosenza (Italy)
2. Observatoire de Paris-Meudon (France)

The one- and two-dimensional behavior of obliquely propagating hydromagnetic waves is analyzed by means of analytical theory and numerical simulations. It is shown that the nonlinear evolution of a one-dimensional MHD wave leads to the formation of a rotational discontinuity and a compressive steepened quasi-linearly polarized pulse whose structure is similar to that of a finite amplitude magnetosonic simple wave. For small propagation angles, the pulse mode (fast or slow) depends on the value of {beta} with respect to unity while for large propagation angles the wave mode is fixed by the sign of the initial density-field correlation. The two-dimensional evolution shows that an MHD wave is unstable against a small-amplitude long-wavelength modulation in the direction transverse to the wave propagation direction. A two-dimensional magnetosonic wave solution is found, in which the density fluctuation is driven by the corresponding total pressure fluctuation, exactly as in the one-dimensional simple wave. Along with the steepening effect, the wave experiences both wave front deformation and a self-focusing effect which may eventually lead to the collapse of the wave. The results compare well with observations of MHD waves in the Earth's foreshock and at comets.

• OSTI ID: 5186759
• Journal Information: Journal of Geophysical Research; (United States), Vol. 96:A5; ISSN 0148-0227
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
HYDROMAGNETIC WAVES
WAVE PROPAGATION
ANALYTICAL SOLUTION
COMETS
COMPARATIVE EVALUATIONS
EARTH MAGNETOSPHERE
INTERACTIONS
IONS
MAGNETOACOUSTIC WAVES
NONLINEAR PROBLEMS
PLASMA DENSITY
REFLECTION
SOLAR WIND
WAVE FORMS
CHARGED PARTICLES
EARTH ATMOSPHERE
EVALUATION
SOLAR ACTIVITY
640201* - Atmospheric Physics- Auroral
Ionospheric
& Magetospheric Phenomena
640107 - Astrophysics & Cosmology- Planetary Phenomena