HR: 1330h
AN: SM52B-0595    [PDF]
TI: Ion cyclotron waves in the high altitude cusp: CLUSTER observations at varying spacecraft separations
AU: * Nykyri, K
EM: k.nykyri@ic.ac.uk
AF: Imperial College, Space and atmospheric physics group, Blackett Laboratory, Prince Consort Road, London, SW7 2BW United Kingdom
AU: Cargill, P
EM: p.cargill@ic.ac.uk
AF: Imperial College, Space and atmospheric physics group, Blackett Laboratory, Prince Consort Road, London, SW7 2BW United Kingdom
AU: Lucek, E
EM: e.lucek@ic.ac.uk
AF: Imperial College, Space and atmospheric physics group, Blackett Laboratory, Prince Consort Road, London, SW7 2BW United Kingdom
AU: Horbury, T
EM: t.horbury@ic.ac.uk
AF: Imperial College, Space and atmospheric physics group, Blackett Laboratory, Prince Consort Road, London, SW7 2BW United Kingdom
AU: Balogh, A
EM: a.balogh@ic.ac.uk
AF: Imperial College, Space and atmospheric physics group, Blackett Laboratory, Prince Consort Road, London, SW7 2BW United Kingdom
AU: Lavraud, B
EM: Benoit.Lavraud@cesr.fr
AF: CESR D‚partement systŠme solaire, 9 avenue du colonel Roche 31028 Toulouse Cedex 4, Toulouse, 31028 France
AU: Fazarkerley, A
EM: anf@mssl.ucl.ac.uk
AF: Mullard Space Science Laboratory, University College London, MSSL, Holmbury St. Mary, Dorking,Surrey, RH5 6NT United Kingdom
AU: Dandouras, I
EM: I.Dandouras@cesr.fr
AF: CESR D‚partement systŠme solaire, 9 avenue du colonel Roche 31028 Toulouse Cedex 4, Toulouse, 31028 France
AU: Reme, H
EM: H.Reme@cesr.fr
AF: CESR D‚partement systŠme solaire, 9 avenue du colonel Roche 31028 Toulouse Cedex 4, Toulouse, 31028 France
AB: We have analysed high-resolution Cluster FGM data (22 vectors/s) during three high-altitude cusp crossings on 17th of March 2001, 2nd and 9th of March 2002. The Cluster separations for these crossings varied between 70 - 600 km and therefore provided an unique opportunity to study wave properties at different length scales. After entering the cusp Cluster observed significant level of magnetic field fluctuations with the highest frequencies scaling as a function of the local ion cyclotron frequency (IC). The waves close to local IC frequency appeared at two types of plasma boundaries: higher amplitude (2-5 nT) incoherent wave packets were observed at regions of enhanced plasma flow, and smaller amplitude ($<$ 0.5 nT), more coherent wave trains were observed at shear flow-stagnant plasma boundary. Sometimes also the first and second harmonic of the dominant frequency were present. Surprisingly the cross-correlation coefficients between spacecraft pair were poor for all crossings indicating that these waves were very locally generated and possibly some wave-particle interactions took place, damping the waves before other spacecraft were able to observe them. Both left-and right-handed waves were observed, and there were no correlation between ellipticities and wave propagation angles with respect to the background magnetic field.
DE: 2724 Magnetopause, cusp, and boundary layers
DE: 2752 MHD waves and instabilities
DE: 7859 Transport processes
DE: 7863 Turbulence
DE: 7867 Wave/particle interactions
SC: SPA - Magnetospheric Physics [SM]
MN: 2003 Fall Meeting