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| Titel |
Spatial aliasing and distortion of energy distribution in the wave vector domain under multi-spacecraft measurements |
| VerfasserIn |
Y. Narita, K.-H. Glassmeier |
| 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 (2009-08-05), S.3031-3042 |
| Datensatznummer |
250016611
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3031-2009.pdf |
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| Zusammenfassung |
| Aliasing is a general problem in the analysis of
any measurements that make sampling at discrete points.
Sampling in the spatial domain results
in a periodic pattern of spectra in the wave vector domain.
This effect is called spatial aliasing, and it is
of particular importance for multi-spacecraft measurements in space.
We first present the theoretical background of aliasing problems
in the frequency domain and generalize it to
the wave vector domain, and then present
model calculations of spatial aliasing.
The model calculations are performed for various configurations
of the reciprocal vectors and energy spectra or distribution
that are placed at different positions in the wave vector domain,
and exhibit two effects on aliasing.
One is weak aliasing, in which the true spectrum
is distorted because of non-uniform aliasing contributions
in the Brillouin zone. It is demonstrated that the energy distribution
becomes elongated in the shortest reciprocal lattice vector
direction in the wave vector domain. The other effect
is strong aliasing, in which aliases have a significant
contribution in the Brillouin zone and the energy distribution
shows a false peak.
These results give a caveat in multi-spacecraft data analysis
in that spectral anisotropy obtained by a measurement has in general two origins:
(1) natural and physical origins like anisotropy imposed
by a mean magnetic field or a flow direction; and (2) aliasing
effects that are imposed by the configuration of the
measurement array (or the set of reciprocal vectors).
This manuscript also discusses a possible method
to estimate aliasing contributions in the Brillouin zone
based on the measured spectrum and to correct the spectra for aliasing. |
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