- Title
- Detection of ultralow-frequency cavity modes using spacecraft data
- Creator
- Waters, C. L.; Takahashi, K.; Lee, D.-H.; Anderson, B. J.
- Relation
- Journal of Geophysical Research: Space Physics Vol. 107, Issue A10
- Publisher Link
- http://dx.doi.org/10.1029/2001JA000224
- Publisher
- American Geophysical Union
- Resource Type
- journal article
- Date
- 2002
- Description
- The cold, magnetized plasma in the Earth's magnetosphere supports two ultralow- frequency plasma wave modes. Both these modes may exhibit resonant oscillations in the magnetosphere cavity. Theoretical and numerical studies have predicted the existence of cavity/waveguide resonance modes, yet experimental evidence is sparse. In this paper we detail the expected structure of these modes using both one dimensional (1-D) and three-dimensional (3-D) magnetohydrodynamic (MHD) numerical models. The cavity/waveguide mode structures are examined in order to develop experimental detection methods suitable for spacecraft electric and magnetic field perturbation data. Cavity mode resonances in the 1-D model suggest a detection method based on wave polarization using the radial (bx) and field-aligned (bz) magnetic perturbations. However, when implemented, this method failed to identify cavity/waveguide modes in the magnetic field data recorded by Active Magnetospheric Particle Tracer Explorers/CCE for events that showed pronounced field line resonances in the azimuthal (by) channel. An examination of data from a 3-D MHD numerical simulation showed that the cavity/waveguide resonant signature was identified best in bz component data. Consequently, a wave mode detection method using the bz data from two spatially separated satellites is discussed. Magnetometer data examples from the ISEE 1 and 2 spacecraft show that field line resonances appear in the by data even when the coherence length of the bz data is less than 0.4 RE.
- Subject
- ULF waves; cavity modes; magnetosphere
- Identifier
- http://hdl.handle.net/1959.13/33828
- Identifier
- uon:3307
- Identifier
- ISSN:0148-0227
- Language
- eng
- Full Text
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