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| Titel |
A study of atmospheric gravity waves and travelling ionospheric disturbances at equatorial latitudes |
| VerfasserIn |
R. L. Balthazor, R. J. Moffett |
| 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. 8 ; Nr. 15, no. 8, S.1048-1056 |
| Datensatznummer |
250012913
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| Publikation (Nr.) |
 copernicus.org/angeo-15-1048-1997.pdf |
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| Zusammenfassung |
| A global coupled thermosphere-ionosphere-plasmasphere
model is used to simulate a family of large-scale imperfectly ducted atmospheric
gravity waves (AGWs) and associated travelling ionospheric disturbances (TIDs)
originating at conjugate magnetic latitudes in the north and south auroral zones
and subsequently propagating meridionally to equatorial latitudes. A 'fast'
dominant mode and two slower modes are identified. We find that, at the magnetic
equator, all the clearly identified modes of AGW interfere constructively and
pass through to the opposite hemisphere with unchanged velocity. At F-region
altitudes the 'fast' AGW has the largest amplitude, and when northward
propagating and southward propagating modes interfere at the equator, the TID
(as parameterised by the fractional change in the electron density at the F2
peak) increases in magnitude at the equator. The amplitude of the TID at the
magnetic equator is increased compared to mid-latitudes in both upper and lower
F-regions with a larger increase in the upper F-region. The ionospheric
disturbance at the equator persists in the upper F-region for about 1 hour and
in the lower F-region for 2.5 hours after the AGWs first interfere, and it is
suggested that this is due to enhancements of the TID by slower AGW modes
arriving later at the magnetic equator. The complex effects of the interplays of
the TIDs generated in the equatorial plasmasphere are analysed by examining
neutral and ion winds predicted by the model, and are demonstrated to be
consequences of the forcing of the plasmasphere along the magnetic field lines
by the neutral air pressure wave. |
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