Journal article
Naturally enhanced ion-acoustic spectra and their interpretation
Incoherent scatter radars are designed to detect scatter from thermal fluctuations in the ionosphere. These fluctuations contain, among other things, features associated with ion-acoustic waves driven by random motions within the plasma. The resulting spectra are generally broad and noisy, but nevertheless the technique can, through a detailed analysis of spectra, be used to measure a range of physical parameters in the Earth's upper atmosphere, and provides a powerful diagnostic in studies of magnetosphere-ionosphere coupling, thermosphere dynamics and the geospace environment in general.
In recent years there has been much interest in naturally occurring (as opposed to artificially stimulated) enhanced ion-acoustic spectra seen in the auroral zone and cusp/cleft region. A study of the plasma instability processes that lead to such spectra will help us to better understand auroral particle acceleration, wave-particle and wave-wave interactions in the ionosphere, and their association with magnetospheric processes.
There is now a substantial body of literature documenting observations of enhanced ion-acoustic spectra, but there remains controversy over generation mechanisms. We present a review of literature documenting observations of naturally enhanced ion-acoustic spectra, observed mainly along the geomagnetic field direction, along with a discussion of the theories put forward to explain such phenomena.
Language: | English |
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Publisher: | Kluwer Academic Publishers |
Year: | 2001 |
Pages: | 55-92 |
Journal subtitle: | An International Review Journal Covering the Entire Field of Geosciences and Related Areas |
ISSN: | 15730956 and 01693298 |
Types: | Journal article |
DOI: | 10.1023/A:1010691026863 |