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| Titel |
Correlation studies for B-spline modeled F2 Chapman parameters obtained from FORMOSAT-3/COSMIC data |
| VerfasserIn |
M. Limberger, W. Liang, M. Schmidt, D. Dettmering, M. Hernández-Pajares, U. Hugentobler |
| 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 ; 32, no. 12 ; Nr. 32, no. 12 (2014-12-17), S.1533-1545 |
| Datensatznummer |
250121141
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| Publikation (Nr.) |
 copernicus.org/angeo-32-1533-2014.pdf |
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| Zusammenfassung |
| The determination of ionospheric key quantities such as the maximum electron
density of the F2 layer NmF2, the corresponding F2 peak height
hmF2 and the F2 scale height HF2 are of high
relevance in 4-D ionosphere modeling to provide information on the vertical
structure of the electron density (Ne). The Ne
distribution with respect to height can, for instance, be modeled by the
commonly accepted F2 Chapman layer. An adequate and observation driven
description of the vertical Ne variation can be obtained from
electron density profiles (EDPs) derived by ionospheric radio occultation
measurements between GPS and low Earth orbiter (LEO) satellites. For these
purposes, the six FORMOSAT-3/COSMIC (F3/C) satellites provide an excellent
opportunity to collect EDPs that cover most of the ionospheric region, in
particular the F2 layer. For the contents of this paper, F3/C EDPs have been
exploited to determine NmF2, hmF2 and
HF2 within a regional modeling approach. As mathematical base
functions, endpoint-interpolating polynomial B-splines are considered to
model the key parameters with respect to longitude, latitude and time. The
description of deterministic processes and the verification of this modeling
approach have been published previously in Limberger et al. (2013), whereas this paper
should be considered as an extension dealing with related correlation
studies, a topic to which less attention has been paid in the literature. Relations
between the B-spline series coefficients regarding specific key parameters as
well as dependencies between the three F2 Chapman key parameters are in the
main focus. Dependencies are interpreted from the post-derived correlation
matrices as a result of (1) a simulated scenario without data gaps by taking
dense, homogenously distributed profiles into account and (2) two real data
scenarios on 1 July 2008 and 1 July 2012 including sparsely, inhomogeneously
distributed F3/C EDPs. Moderate correlations between hmF2
and HF2 as well as inverse correlations between NmF2 and
HF2 are reflected from the simulation. By means of the real data
studies, it becomes obvious that the sparse measurement distribution leads to
an increased weighting of the prior information and suppresses the parameter
correlations which play an important role regarding the parameter
estimability. The currently implemented stochastic model is in need of
improvement and does not consider stochastic correlations which consequently
cannot occur. |
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