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Electromagnetic ion cyclotron waves observed in the plasma depletion layer
Author(s) -
Anderson B. J.,
Fuselier S. A.,
Murr D.
Publication year - 1991
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 - 10.1029/91gl02238
Subject(s) - magnetosheath , physics , cyclotron , solar wind , anisotropy , plasma , ion , magnetic field , proton , atomic physics , computational physics , transverse plane , geophysics , optics , magnetopause , nuclear physics , quantum mechanics , structural engineering , engineering
Observations from AMPTE/CCE in the Earth's magnetosheath on October 5, 1984 are presented to illustrate 0.1–4.0 Hz magnetic field pulsations in the subsolar plasma depletion layer (PDL) for northward sheath field during a magnetospheric compression. The PDL is unambiguously identified by comparing CCE data with data from IRM in the upstream solar wind. Pulsations in the PDL are dominated by transverse waves with F/F H + ≤ 1.0 and a slot in spectral power at F/F H + = 0.5. The upper branch is left hand polarized while the lower branch is linearly polarized. In the sheath the proton temperature anisotropy, A = T⟂/T∥ − 1, is ≈ 0.6 but it is ≈ 1.7 in the PDL during wave occurrence. The properties and correlation of waves with increased anisotropy indicate that they are electromagnetic ion cyclotron waves.