|
|
 |
|
|
Ann. Geophys., 23, 2861-2866, 2005
www.ann-geophys.net/23/2861/2005/
© European Geosciences Union 2005
Observations of lion roars in the magnetosheath by the STAFF/DWP experiment on the Double Star TC-1 spacecraft
K. H. Yearby1, H. S. C. Alleyne1, N. Cornilleau-Wehrlin2, O. Santolik3,4, M. A. Balikhin1, S. N. Walker1, A. Fazakerley5, and A. Lahiff5
1ACSE, University of Sheffield, Mappin Street, Sheffield, S1 3JD, UK
2CETP/IPSL, 10–12 Av. de l’Europe, 78 140 Vélizy, France
3Faculty of Mathematics and Physics, Charles University, V Holesovickach 2, 18 000 Praha 8, Czech Republic
4Institute of Atmospheric Physics, Bocni II/1401, 14 131 Praha 4, Czech Republic
5Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
Abstract. Lion roars are intense, short duration packets of whistler mode waves,
observed in the magnetosheath. They are typically seen coincident with the
magnetic field minima of mirror mode waves. The orbit of the Double Star TC-1
spacecraft (570 km by 78970 km, inclination at 28.5 degrees) is ideal for
observations of lion roars as the spacecraft is in the magnetosheath more
than 50% of the time when the apogee is on the dayside. The STAFF/DWP
experiment provides the spectral matrix of the three magnetic components at
27 frequencies in the range 10 Hz to 4 kHz, with one second time resolution,
and also the waveform up to 180 Hz at a low duty cycle. The characteristics
of lion roars observed are reported. The maximum lion roar intensities
appear higher than reported by most previous studies. The electron
temperature anisotropy is estimated from the lion roar frequency ratios, and
is in reasonably good agreement with plasma measurements. This indicates the
presence of a trapped electron component in the mirror mode.
Full Article in PDF (6700 KB) |
|
|
