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| Titel |
Modeling ionospheric foF2 by using empirical orthogonal function analysis |
| VerfasserIn |
Ercha Aa, D.-H. Zhang, Z. Xiao, Y.-Q. Hao, A. J. Ridley, M. Moldwin |
| 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 ; 29, no. 8 ; Nr. 29, no. 8 (2011-08-31), S.1501-1515 |
| Datensatznummer |
250017082
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| Publikation (Nr.) |
 copernicus.org/angeo-29-1501-2011.pdf |
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| Zusammenfassung |
| A similar-parameters interpolation method and an empirical orthogonal
function analysis are used to construct empirical models for the ionospheric
foF2 by using the observational data from three ground-based ionosonde
stations in Japan which are Wakkanai (Geographic 45.4° N,
141.7° E), Kokubunji (Geographic 35.7° N, 140.1° E) and
Yamagawa (Geographic 31.2° N, 130.6° E) during the years of
1971–1987. The impact of different drivers towards ionospheric foF2 can be
well indicated by choosing appropriate proxies. It is shown that the missing
data of original foF2 can be optimal refilled using similar-parameters
method. The characteristics of base functions and associated coefficients of
EOF model are analyzed. The diurnal variation of base functions can reflect
the essential nature of ionospheric foF2 while the coefficients represent the
long-term alteration tendency. The 1st order EOF coefficient A1 can
reflect the feature of the components with solar cycle variation. A1
also contains an evident semi-annual variation component as well as a
relatively weak annual fluctuation component. Both of which are not so
obvious as the solar cycle variation. The 2nd order coefficient A2
contains mainly annual variation components. The 3rd order coefficient
A3 and 4th order coefficient A4 contain both annual and
semi-annual variation components. The seasonal variation, solar rotation
oscillation and the small-scale irregularities are also included in the
4th order coefficient A4. The amplitude range and developing
tendency of all these coefficients depend on the level of solar activity and
geomagnetic activity. The reliability and validity of EOF model are verified
by comparison with observational data and with International Reference
Ionosphere (IRI). The agreement between observations and EOF model is quite
well, indicating that the EOF model can reflect the major changes and the
temporal distribution characteristics of the mid-latitude ionosphere of the
Sea of Japan region. The error analysis processes imply that there are
seasonal anomaly and semi-annual asymmetry phenomena which are consistent
with pre-existing ionosphere theory. |
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