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| Titel |
Solar and geomagnetic activity effects on mid-latitude F-region electric fields |
| VerfasserIn |
V. V. Kumar, M. L. Parkinson, P. L. Dyson, R. Polglase |
| 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 ; 26, no. 9 ; Nr. 26, no. 9 (2008-09-24), S.2911-2921 |
| Datensatznummer |
250016237
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| Publikation (Nr.) |
 copernicus.org/angeo-26-2911-2008.pdf |
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| Zusammenfassung |
| Diurnal patterns of average F-region ionospheric drift
(electric field) and their dependence on solar and geomagnetic activity have
been defined using digital ionosonde Doppler measurements recorded at a
southern mid-latitude station (Bundoora 145.1° E, 37.7° S geographic,
49° S magnetic). A unique database consisting of 300 907 drift velocities
was compiled, mostly using one specific mode of operation throughout 1632
days of a 5-year interval (1999–2003). The velocity magnitudes were
generally larger during the night than day, except during the winter months
(June–August), when daytime velocities were enhanced. Of all years, the
largest drifts tended to occur during the high speed solar wind streams of
2003. Diurnal patterns in the average quiet time (AE<75 nT) meridional
drifts (zonal electric field) peaked at up to ~6 m s−1 poleward
(0.3 mV m−1 eastward) at 03:30 LST, reversing in direction at ~08:30 LST,
and gradually reaching ~10 m s−1 equatorward at ~13:30 LST.
The quiet time zonal drifts (meridional electric fields)
displayed a clear diurnal pattern with peak eastward flows of ~10 m s−1
(0.52 mV m−1 equatorward) at 09:30 LST and peak westward flows
around midnight of ~18 m s−1 (0.95 mV m−1 poleward). As the
AE index increased, the westward drifts increased in amplitude and they
extended over a greater fraction of the day. The perturbation drifts changed
in a similar way with decreasing Dst except the daytime equatorward flows
strengthened with increasing AE index, whereas they became weak for
Dst<−60 nT. The responses in all velocity components to changing solar
flux values were small, but net poleward perturbations during the day were
associated with large solar flux values (>192×10−22 W m−2 Hz−1).
These results help to more fully quantify the response
of the mid-latitude ionosphere to changing solar and geomagnetic conditions,
as required to refine empirical and theoretical models of mid-latitude
electric fields. |
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