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| Titel |
The uncertainty of local background magnetic field orientation in anisotropic plasma turbulence |
| VerfasserIn |
Felix Gerick, Joachim Saur, Michael von Papen |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250148258
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| Publikation (Nr.) |
 EGU/EGU2017-12498.pdf |
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| Zusammenfassung |
| In order to resolve and characterize anisotropy in turbulent plasma flows a proper estimation
of the background magnetic field is crucially important. Various approaches to calculate the
background magnetic fields, ranging from local fields to globally averaged fields, are
commonly used in the analysis of turbulent data. Here we investigate how the uncertainty in
the orientation of a scale dependent background magnetic field influences the ability to
resolve anisotropy. Therefore we introduce a quantitative measure, the uncertainty angle,
which characterizes the uncertainty of the orientation of the background magnetic field
turbulent structures are exposed to. The angle uncertainty can be used as a condition
to estimate the ability to resolve anisotropy with certain accuracy. We apply our
description to resolve spectral anisotropy in fast solar wind data. We show that if
the uncertainty angle grows too large, the power of the turbulent fluctuations is
attributed to false local magnetic field angles, which affects the spectral anisotropy.
However, the anisotropy in the spectral index remains intact until very large averaging
widths due to unequal change of power depending on the frequency. The frequency
dependent angle uncertainty is a measure which can be applied to any turbulent system. |
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