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| Titel |
A note on chaotic vs. stochastic behavior of the high-latitude ionospheric plasma density fluctuations |
| VerfasserIn |
A. W. Wernik, K. C. Yeh |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1023-5809
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| Digitales Dokument |
URL |
| Erschienen |
In: Nonlinear Processes in Geophysics ; 3, no. 1 ; Nr. 3, no. 1, S.47-57 |
| Datensatznummer |
250000703
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| Publikation (Nr.) |
 copernicus.org/npg-3-47-1996.pdf |
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| Zusammenfassung |
| Four data sets of density
fluctuations measured in-situ by the Dynamics Explorer (DE 2) were analyzed
in an
attempt to study chaotic nature of the
high-latitude
turbulence and, in this way to complement the
conventional
spectral analysis. It has been found that the
probability
distribution function of density differences is
far from
Gaussian and similar to that observed in the
intermittent
fluid or MBD turbulence. This indicates that
ionospheric
density fluctuations are not stochastic but coherent
to some
extent. Wayland's and surrogate data tests for
determinism in
a time series of density data allowed us to
differentiate
between regions of intense shear and moderate
shear. We
observe that in the region of strong field aligned
currents (FAC) and intense shear, or along the convection
in the
collisional regime, ionospheric turbulence behaves
like a
random noise with non-Gaussian statistics implying
that the
underlying physical process is nondeterministic. On the
other
hand, when FACs are weak, and shear is
moderate or
observations made in the inertial regime the
turbulence is
chaotic. The attractor dimension is lowest (1.9) for
"old"
convected irregularities. The dimension 3.2 is
found for
turbulence in the inertial regime and considerably
smaller
(2.4) in the collisional regime. It is suggested that
a high
dimension in the inertial regime may be caused
by a
complicated velocity structure in the shear
instability
region. |
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