Magnetospheric lion roars

Citation
W. Baumjohann et al., Magnetospheric lion roars, ANN GEOPH, 18(4), 2000, pp. 406-410
Citations number
10
Categorie Soggetti
Space Sciences
Journal title
ANNALES GEOPHYSICAE-ATMOSPHERES HYDROSPHERES AND SPACE SCIENCES
ISSN journal
09927689 → ACNP
Volume
18
Issue
4
Year of publication
2000
Pages
406 - 410
Database
ISI
SICI code
0992-7689(200004)18:4<406:MLR>2.0.ZU;2-E
Abstract
The Equator-S magnetometer is very sensitive and has a sampling rate normal ly of 128 Hz. The high sampling rate for the first time allows detection of ELF waves between the ion cyclotron and the lower hybrid frequencies in th e equatorial dawnside magnetosphere. The characteristics of these waves are virtually identical to the lion roars typically seen at the bottom of the magnetic troughs of magnetosheath mirror waves. The magnetospheric lion roa rs are near-monochromatic packets of electron whistler waves lasting for a few wave cycles only, typically 0.2 s. They are right-hand circularly polar ized waves with typical amplitudes of 0.5 nT at around one tenth of the ele ctron gyrofrequency. The cone angle between wave vector and ambient field i s nearly always smaller than 1 degrees.