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| Titel |
Modification of conductivity due to acceleration of the ionospheric medium |
| VerfasserIn |
V. V. Denisenko, H. K. Biernat, A. V. Mezentsev, V. A. Shaidurov, S. S. Zamay |
| 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. 8 ; Nr. 26, no. 8 (2008-07-31), S.2111-2130 |
| Datensatznummer |
250016173
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| Publikation (Nr.) |
 copernicus.org/angeo-26-2111-2008.pdf |
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| Zusammenfassung |
A quantitative division of the ionosphere into dynamo and motor regions
is performed on the base of empirical models of space distributions of ionospheric parameters.
Pedersen and Hall conductivities are modified to represent
an impact of acceleration of the medium because of Ampére's force.
It is shown that the currents in the F2 layer are greatly reduced
for processes of a few hours duration.
This reduction is in particular important for the night-side low-latitude ionosphere.
The International Reference Ionosphere model is used
to analyze the effect quantitatively.
This model gives a second high conducting layer in the night-side
low-latitude ionosphere that reduces the electric field
and equatorial electrojets, but intensifies
night-side currents during the short-term events.
These currents occupy regions which are much wider than those
of equatorial electrojets.
It is demonstrated that the parameter σd=σP+σHΣH/ΣP
that involves
the integral Pedersen and Hall conductances ΣP, ΣH
ought to be used instead of the local Cowling conductivity σC
in calculations of the electric current density in the equatorial ionosphere.
We may note that Gurevich et al. (1976) derived a parameter similar to σd
for more general conditions as those which we discuss in this paper;
a more detailed description of this point is given in Sect. 6.
Both, σd and σC, appear when a magnetic field line is near a nonconducting domain which means
zero current through the boundary of this domain.
The main difference between σd and σC is that σd definition
includes the possibility for the electric current
to flow along a magnetic field line in order to close all currents which go to this line from neighboring ones.
The local Cowling conductivity σC corresponds to the current closure at each point of a magnetic field line.
It is adequate only for a magnetic field line with constant local conductivity at the whole line
when field-aligned currents do not exist because of symmetry, but σC=σd in this case.
So, there is no reason to use the local Cowling conductivity while the Cowling conductance
ΣC=ΣP+ΣH2/ΣP is a useful and well defined parameter. |
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