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| Titel |
Evidence and effects of a wave-driven nonlinear current in the equatorial electrojet |
| VerfasserIn |
M. Oppenheim |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
0992-7689
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| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 15, no. 7 ; Nr. 15, no. 7, S.899-907 |
| Datensatznummer |
250012874
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| Publikation (Nr.) |
 copernicus.org/angeo-15-899-1997.pdf |
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| Zusammenfassung |
| Ionospheric two-stream waves and
gradient-drift waves nonlinearly drive a large-scale (D.C.) current in the E-region
ionosphere. This current flows parallel to, and with a comparable magnitude to,
the fundamental Pedersen current. Evidence for the existence and magnitude of
wave-driven currents derives from a theoretical understanding of E-region
waves, supported by a series of nonlinear 2D simulations of two-stream waves and
by data collected by rocket instruments in the equatorial electrojet.
Wave-driven currents will modify the large-scale dynamics of the equatorial
electrojet during highly active periods. A simple model shows how a wave-driven
current appreciably reduces the horizontally flowing electron current of the
electrojet. This reduction may account for the observation that type-I radar
echoes almost always have a Doppler velocity close to the acoustic speed, and
also for the rocket observation that electrojet regions containing
gradient-drift waves do not appear also to contain horizontally propagating
two-stream waves. Additionally, a simple model of a gradient-drift instability
shows that wave-driven currents can cause nonsinusoidal electric fields similar
to those measured in situ. |
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