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| Titel |
Role of inductive electric fields and currents in dynamical ionospheric situations |
| VerfasserIn |
H. Vanhamäki, O. Amm, A. Viljanen |
| 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 ; 25, no. 2 ; Nr. 25, no. 2 (2007-03-08), S.437-455 |
| Datensatznummer |
250015789
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| Publikation (Nr.) |
 copernicus.org/angeo-25-437-2007.pdf |
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| Zusammenfassung |
| We study the role of ionospheric induction in different commonly observed
ionospheric situations. These include an intensifying electrojet, westward
travelling surge (WTS) and Ω-band. We use data based, realistic models
for these phenomena and calculate the inductive electric fields that are
created due to the temporal variations of ionospheric currents. The
ionospheric induction problem is solved using a new calculation technique
that can handle non-uniform, time-dependent conductances and electric fields
of any geometry. We find that in some situations inductive effects are not
negligible and the ionospheric electric field is not a pure potential field,
but has a significant induced rotational part. In the WTS and Ω-band
models the induced electric field is concentrated in a small area, where the
time derivatives are largest. In the electrojet model the induced field is
significant over a large part of the jet area. In these examples the induced
electric field has typical values of few mV/m, which amounts to
several tens of percents of the potential electric field present at the same
locations. The induced electric field is associated with ionospheric and
field aligned currents (FAC), that modify the overall structure of the
current systems. Especially the induced FAC are often comparable to the
non-inductive FAC, and may thus modify the coupling between the ionosphere
and magnetosphere in the most dynamical situations. We also present some
examples with very simple ionospheric current systems, where the effect of
different ionospheric parameters on the induction process is studied. |
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