 |
| Titel |
An interpretation of the ƒoF2 and hmF2 long-term trends in the framework of the geomagnetic control concept |
| VerfasserIn |
A. V. Mikhailov, D. Marin |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 19, no. 7 ; Nr. 19, no. 7, S.733-748 |
| Datensatznummer |
250014285
|
| Publikation (Nr.) |
 copernicus.org/angeo-19-733-2001.pdf |
|
|
|
|
|
| Zusammenfassung |
Earlier revealed
morphological features of the foF2 and hmF2 long-term trends are
interpreted in the scope of the geomagnetic control concept based on the
contemporary F2-layer storm mechanisms. The F2-layer parameter trends strongly
depend on the long-term varying geomagnetic activity whose effects cannot be
removed from the trends using conventional indices of geomagnetic activity.
Therefore, any interpretation of the foF2 and hmF2 trends should
consider the geomagnetic effects as an inalienable part of the trend analysis.
Periods with negative and positive foF2 and hmF2 trends
correspond to the periods of increasing or decreasing geomagnetic activity with
the turning points around 1955, and the end of 1960s and 1980s, where foF2
and hmF2 trends change their signs. Such variations can be explained by
neutral composition, as well as temperature and thermospheric wind changes
related to geomagnetic activity variations. In particular, for the period of
increasing geomagnetic activity (1965–1991) positive at lower latitudes, but
negative at middle and high latitudes, foF2 trends may be explained by
neutral composition and temperature changes, while soft electron precipitation
determines nighttime trends at sub-auroral and auroral latitudes. A pronounced
dependence of the foF2 trends on geomagnetic (invariant) latitude and
the absence of any latitudinal dependence for the hmF2 trends are due to
different dependencies of NmF2 and hmF2 on main aeronomic parameters.
All of the revealed latitudinal and diurnal foF2 and hmF2 trend
variations may be explained in the frame-work of contemporary F2-region storm
mechanisms. The newly proposed geomagnetic storm concept used to explain
F2-layer parameter long-term trends proceeds from a natural origin of the
trends rather than an artificial one, related to the thermosphere cooling due
to the greenhouse effect. Within this concept, instead of cooling, one should
expect the thermosphere heating for the period of increasing geomagnetic
activity (1965–1991).
Key words. Ionosphere
(ionosphere-atmosphere interactions; ionospheric disturbances) |
| |
|
| Teil von |
|
|
|
|
|
|
|
|