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| Titel |
Transient production of F-region irregularities associated with TCV passage |
| VerfasserIn |
R. Kataoka, H. Fukunishi, K. Hosokawa, H. Fujiwara, A. S. Yukimatu, N. Sato, Y.-K. Tung |
| 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 ; 21, no. 7 ; Nr. 21, no. 7, S.1531-1541 |
| Datensatznummer |
250014660
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| Publikation (Nr.) |
 copernicus.org/angeo-21-1531-2003.pdf |
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| Zusammenfassung |
Transient production of
F-region plasma irregularities due to traveling convection vortices (TCVs) was
investigated using the Super Dual Auroral Radar Network (SuperDARN) combined
with ground magnetometer networks and the POLAR ultraviolet imager. We selected
two large-amplitude (100–200 nT) TCV events that occurred on 22 May 1996 and
24 July 1996. It is found that the TCV-associated HF backscatter arises in
blobs with spatial scale of a few hundreds km. They traveled following tailward
bulk motion of the TCV across the three fields-of-view of the SuperDARN HF
radars in the prenoon sector. The spectra in the blobs showed unidirectional
Doppler velocities of typically 400–600 m/s, with flow directions away from
the radar. These unidirectional velocities correspond to the poleward and/or
eastward convective flow near the leading edge of upward field-aligned current.
The backscatter blobs overlapped the poleward and westward part of the TCV-related
transient aurora. It is likely that the transient backscatter blobs are
produced by the three-dimensional gradient drift instabilities in the
three-dimensional current system of the TCV. In this case, nonlinear rapid
evolution of irregularities would occur in the upward field-aligned current
region. The spectral width of the backscatter blob is typically distributed
between 50 and 300 m/s, but sometimes it is over 400 m/s. This suggests that
the temporal broad spectra over 400 m/s are produced by Pc1–2 bursts, while
the background spectral width of 50–300 m/s are produced by the velocity
gradient structure of convection vortices themselves.
Key words. Ionosphere (Electric
fields and currents; Ionospheric irregularities; Plasma convection) |
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