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| Titel |
A global model of the ionospheric F2 peak height based on EOF analysis |
| VerfasserIn |
M.-L. Zhang, C. Liu, W. Wan, L. Liu, B. Ning |
| 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 ; 27, no. 8 ; Nr. 27, no. 8 (2009-08-14), S.3203-3212 |
| Datensatznummer |
250016625
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3203-2009.pdf |
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| Zusammenfassung |
| The ionospheric F2 peak height hmF2 is an important
parameter that is much needed in ionospheric research and practical
applications. In this paper, an attempt is made to develop a global
model of hmF2. The hmF2 data, used to construct
the global model, are converted from the monthly median hourly
values of the ionospheric propagation factor M(3000)F2 observed by
ionosondes/digisondes distributed globally, based on the strong
anti-correlation existed between hmF2 and M(3000)F2. The
empirical orthogonal function (EOF) analysis method, combined with
harmonic function and regression analysis, is used to construct the
model. The technique used in the global modelling involves two
layers of EOF analysis of the dataset. The first layer EOF analysis
is applied to the hmF2 dataset which decomposed the dataset
into a series of orthogonal functions (EOF base functions) Ek and
their associated EOF coefficients Pk. The base functions Ek
represent the intrinsic characteristic variations of the dataset
with the modified dip latitude and local time, the coefficients
Pk represents the variations of the dataset with the universal
time, season as well as solar cycle activity levels. The second
layer EOF analysis is applied to the EOF coefficients Pk obtained
in the first layer EOF analysis. The coefficients Ak, obtained in
the second layer EOF analysis, are then modelled with the harmonic
functions representing the seasonal (annual and semi-annual) and
solar cycle variations, with their amplitudes changing with the
F10.7 index, a proxy of the solar activity level. Thus, the
constructed global model incorporates the geographical location,
diurnal, seasonal as well as solar cycle variations of hmF2
through the combination of EOF analysis and the harmonic function
expressions of the associated EOF coefficients. Comparisons between
the model results and observational data were consistent, indicating
that the modelling technique used is very promising when used to
construct the global model of hmF2 and it has the potential
of being used for the global modelling/mapping of other ionospheric
parameters. Statistical analysis on model-data comparison showed
that our constructed model of hmF2, based on the EOF
expansion method, compares better with the observational data than
the model currently used in the International Reference Ionosphere
(IRI) model. |
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