 |
| Titel |
Ionospheric climatology and variability from long-term and multiple incoherent scatter radar observations: variability |
| VerfasserIn |
S.-R. Zhang, J. M. Holt |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
0992-7689
|
| Digitales Dokument |
URL |
| Erschienen |
In: Annales Geophysicae ; 26, no. 6 ; Nr. 26, no. 6 (2008-06-11), S.1525-1537 |
| Datensatznummer |
250016123
|
| Publikation (Nr.) |
 copernicus.org/angeo-26-1525-2008.pdf |
|
|
|
|
|
| Zusammenfassung |
| Long-term incoherent scatter radar (ISR) observations are used to study
ionospheric variability for two midlatitude sites, Millstone Hill and St. Santin.
This work is based on our prior efforts which resulted in an
empirical model system, ISR Ionospheric Model (ISRIM), of climatology (and
now variability) of the ionosphere. We assume that the variability can be
expressed in three terms, the background, solar activity and geomagnetic
activity components, each of which is a function of local time, season and
height. So the background variability is ascribed mostly to the day-to-day
variability arising from non solar and geomagnetic activity sources. (1)
The background variability shows clear differences between the bottomside
and the topside and changes with season. The Ne variability is low in the
bottomside in summer, and high in the topside in winter and spring. The
plasma temperature variability increases with height, and reaches a
minimum in summer. Ti variability has a marked maximum in spring; at
Millstone Hill it is twice as high as at St. Santin. (2) For enhanced
solar activity conditions, the overall variability in Ne is reduced in the
bottomside of the ionosphere and increases in the topside. For Te, the
solar activity enhancement reduces the variability in seasons of high
electron density (winter and equinox) at altitudes of high electron
density (near the F2-peak). For Ti, however, while the variability tends
to decrease at Millstone Hill (except for altitudes near 200 km), it
increases at St. Santin for altitudes up to 350 km; the solar flux
influence on the variability tends to be stronger at St. Santin than at
Millstone Hill. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|