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Dispersion analysis of ULF waves in the foreshock using cluster data and the wave telescope technique
Author(s) -
Narita Y.,
Glassmeier K.H.,
Schäfer S.,
Motschmann U.,
Sauer K.,
Dandouras I.,
Fornaçon K.H.,
Georgescu E.,
Rème H.
Publication year - 2003
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 - 10.1029/2003gl017432
Subject(s) - physics , foreshock , dispersion relation , dispersion (optics) , bow shock (aerodynamics) , wave propagation , computational physics , geophysics , doppler effect , population , rest frame , shock wave , astrophysics , geology , optics , seismology , astronomy , aftershock , mechanics , demography , redshift , sociology , galaxy
Cluster provides us with a unique possibility to study ULF waves. We analyze ULF wave activity in the near‐Earth upstream solar wind. Using Cluster as a wave telescope we investigate in detail wave propagation directions and wave numbers for various frequencies, obtaining, for the first time, three dimensional dispersion relations experimentally. After Doppler shift correction, we find that the dispersion relations are not linear and the waves are propagating in the sunward direction in the plasma rest frame. Comparison of the experimentally derived dispersion relation with that one for a beam plasma system shows good agreement. We suggest that the ULF waves in the foreshock are generated by a proton population backstreaming from the shock.