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Ion cyclotron waves in the high altitude cusp: CLUSTER observations at varying spacecraft separations
Author(s) -
Nykyri K.,
Cargill P. J.,
Lucek E. A.,
Horbury T. S.,
Balogh A.,
Lavraud B.,
Dandouras I.,
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 - 10.1029/2003gl018594
Subject(s) - spacecraft , cusp (singularity) , physics , cyclotron , cluster (spacecraft) , plasma , magnetic field , effects of high altitude on humans , astrophysics , ion , altitude (triangle) , computational physics , geophysics , astronomy , nuclear physics , meteorology , geometry , mathematics , quantum mechanics , computer science , programming language
We have analysed high‐resolution Cluster magnetic field data during three high‐altitude cusp crossings in 2001 and 2002. The Cluster separations for these crossings varied between 100 and 600 km and therefore provided an unique opportunity to study wave properties at different length scales. In the cusp Cluster sees frequent intervals of magnetic field fluctuations with clear peaks in power close to the local ion cyclotron frequency, and both left‐ and right‐handed polarisations. At large separations the power seen at different spacecraft can differ by orders of magnitude. For smaller separations, the power seen at the four spacecraft agrees better but still shows some differences. For all separations there was no significant correlation between the signals seen at different spacecraft, indicative of very local structure. The origin of the waves appears to lie in highly filamented sheared plasma flows present in the cusp.