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| Titel |
Response of equatorial ionosphere to episodes of asymmetric ring current activity |
| VerfasserIn |
J. H. Sastri, M. A. Abdu, J. H. A. Sobral |
| 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. 10 ; Nr. 15, no. 10, S.1316-1323 |
| Datensatznummer |
250012978
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| Publikation (Nr.) |
 copernicus.org/angeo-15-1316-1997.pdf |
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| Zusammenfassung |
| We present the characteristics of the
response of equatorial ionospheric zonal electric field and F-region plasma
density to the asymmetric ring current intensifications that occurred in
succession on 16 December 1991, corresponding to the STEP/EITS-2 campaign
period. The study is based on high-time- resolution (1-min) data of asymmetic
ring current indices, ASY(H/D) and F-region vertical plasma drift, Vz
measurements at Kodaikanal (10.25°N; 77.5°E; dip 4°), India and
quarter-hourly ionosonde data of Fortaleza (4°S; 322°E; dip –9°), Brazil. It
is shown that short-lived disturbances in F-layer vertical plasma drift, Vz
and height (h'F/hpF2) indicative of westward and eastward electric fields
prevail simultaneously in the dusk (18–21 LT) and predawn (02–05 LT) sectors,
respectively, in association with the decay phase of asymmetic ring current
events. Electric fields of opposite polarity do also seem to manifest at these
local times, particularly in the early-morning sector in conjunction with the
intensification of the asymmetric ring current. At a given location, electric
field disturbances associated with individual asymmetric ring current events are
thus bipolar in nature, with fields of opposite polarity during the growth and
decay phases. The nature and polarity structure of the observed electric field
disturbances are in agreement with the theoretical/model predictions of prompt
penetration of high-latitude electric fields to the equatorial region. |
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