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| Titel |
The statistical properties of spread F observed at Hainan station during the declining period of the 23rd solar cycle |
| VerfasserIn |
G. J. Wang, J. K. Shi, X. Wang, S. P. Shang, G. Zherebtsov, O. M. Pirog |
| 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 ; 28, no. 6 ; Nr. 28, no. 6 (2010-06-10), S.1263-1271 |
| Datensatznummer |
250016842
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| Publikation (Nr.) |
 copernicus.org/angeo-28-1263-2010.pdf |
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| Zusammenfassung |
| The temporal variations of the low latitude nighttime
spread F (SF) observed by DPS-4 digisonde at low latitude Hainan
station (geog. 19.5° N, 109.1° E, dip lat. 9.5° N) during the
declining solar cycle 23 from March 2002 to February 2008 are
studied. The spread F measured by the digisonde were classified into
four types, i.e., frequency SF (FSF), range SF (RSF), mixed SF
(MSF), and strong range SF (SSF). The statistical results show that
MSF and SSF are the outstanding irregularities in Hainan, MSF mainly
occurs during summer and low solar activity years, whereas SSF
mainly occurs during equinoxes and high solar activity years. The
SSF has a diurnal peak before midnight and usually appears during
20:00–02:00 LT, whereas MSF peaks nearly or after midnight and occurs
during 22:00–06:00 LT. The time of maximum occurrence of SSF is later
in summer than in equinoxes and this time delay can be caused by the
later reversal time of the E×B drift in
summer. The SunSpot Number (SSN) dependence of each type SF is different during
different season. The FSF is independent of SSN during each season;
RSF with SSN is positive relation during equinoxes and summer and is
no relationship during the winter; MSF is significant dependence on
SSN during the summer and winter, and does not relate to SSN during
the equinoxes; SSF is clearly increasing with SSN during equinoxes
and summer, while it is independent of SSN during the winter. The
occurrence numbers of each type SF and total SF have the same trend,
i.e., increasing as Kp increases from 0 to 1, and then decreasing as
increasing Kp. The correlation with Kp is negative for RSF, MSF, SSF
and total SF, but is vague for the FSF. |
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