- Title
- Electromagnetic ion cyclotron waves in the magnetosphere
- Creator
- Fraser, B. J.; Loto'aniu, T. M.; Singer, H. J.
- Relation
- Magnetospheric ULF Waves: Synthesis and New Directions p. 195-212
- Relation
- http://www.agu.org/cgi-bin/agubooks?book=SPGM1694344
- Publisher
- American Geophysical Union
- Resource Type
- book chapter
- Date
- 2006
- Description
- Electromagnetic ion cyclotron (EMIC) waves are generated in the equatorial region of the plasmasphere-magnetosphere by internal wave-particle interaction with ring current ions. In ground observations they are observed as Pc 1-2 (0.1-5 Hz) waves, and one group of waves exhibits a spectral fine structure that has been classically explained by bouncing packet field-aligned propagation. An unstructured class of Pc 1-2 waves, including intervals of pulsations with diminishing period, lacks a fine structure pattern and is the dominant emission observed in the middle and outer magnetosphere by satellites. Poynting flux observations show that wave energy propagates unidirectionally away from the equatorial region, which does not support the bouncing wave packet paradigm. The cold/cool magnetospheric plasma has a profound effect on the generation and spectral properties of EMIC waves. The waves are often observed at geostationary orbit within the outer magnetosphere extension of plasmaspheric plasma plumes seen by the IMAGE spacecraft in the extreme ultraviolet (EUV) imager instrument and associated with subauroral proton arcs seen by the far ultraviolet (FUV) imager. This provides evidence in support of a ring current loss mechanism induced by pitch angle scattering of protons by EMIC waves. Characteristic frequencies introduced into the cold/cool plasma by heavy O[+] and He[+] ions determine the EMIC wave spectra and these may be used in plasma diagnostic studies. Outstanding issues considered include the possible role of the ionospheric Alfvén resonator in EMIC wave generation, and the modulation of EMIC waves by Pc 3-5 long-period ULF waves.
- Subject
- electromagnetic ion cyclotron waves; plasmasphere; magnetosphere; ring current ions; ionospheric Alfvén resonator; ULF waves
- Identifier
- uon:2240
- Identifier
- http://hdl.handle.net/1959.13/28827
- Identifier
- ISBN:9780875904344
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