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High‐frequency wave normals in the solar wind
Author(s) -
Herbert Floyd,
Smith Larry D.,
Sonett C. P.
Publication year - 1984
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/gl011i005p00492
Subject(s) - ecliptic , physics , solar wind , population , astrophysics , isotropy , bow shock (aerodynamics) , computational physics , magnetic field , geophysics , atmospheric sciences , optics , shock wave , mechanics , demography , quantum mechanics , sociology
High‐frequency (0.01 ‐ 0.04 Hz) magnetic fluctuations in 506 ten‐minute intervals of contemporaneous Explorer 35 and Apollo 12 measurements made in the solar wind near the morning side of the Earth's bow shock show the presence of a large population of disturbances resembling Alfvén waves. Each wavefront normal n is systematically aligned (median deviation = 35°) with < B >, the associated ten‐minute average of the magnetic field. Because of variability in the direction of < B > from one interval to another, the coupled distribution of n is nearly isotropic in solar ecliptic coordinates, in contrast with the results of other studies of waves at much lower frequency indicating outward propagation from the sun. Presumably the high frequency waves discussed here are stirred into isotropy (in solar ecliptic coordinates) by following the low frequency fluctuations. As these waves maintain their alignment of n with < B > despite the great variation of < B >, a strong physical alignment constraint is inferred.