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| Titel |
The application of a shift theorem analysis technique to multipoint measurements |
| VerfasserIn |
M. E. Dieckmann, S. C. Chapman |
| 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 ; 17, no. 3 ; Nr. 17, no. 3, S.321-327 |
| Datensatznummer |
250013688
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| Publikation (Nr.) |
 copernicus.org/angeo-17-321-1999.pdf |
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| Zusammenfassung |
A Fourier domain technique has been proposed
previously which, in principle, quantifies the extent to which multipoint
in-situ measurements can identify whether or not an observed structure is time
stationary in its rest frame. Once a structure, sampled for example by four
spacecraft, is shown to be quasi-stationary in its rest frame, the structure's
velocity vector can be determined with respect to the sampling spacecraft. We
investigate the properties of this technique, which we will refer to as a
stationarity test, by applying it to two point measurements of a simulated
boundary layer. The boundary layer was evolved using a PIC (particle in cell)
electromagnetic code. Initial and boundary conditions were chosen such, that two
cases could be considered, i.e. a spacecraft pair moving through (1) a time
stationary boundary structure and (2) a boundary structure which is evolving
(expanding) in time. The code also introduces noise in the simulated data time
series which is uncorrelated between the two spacecraft. We demonstrate that,
provided that the time series is Hanning windowed, the test is effective in
determining the relative velocity between the boundary layer and spacecraft and
in determining the range of frequencies over which the data can be treated as
time stationary or time evolving. This work presents a first step towards
understanding the effectiveness of this technique, as required in order for it
to be applied to multispacecraft data.
Key words. Electromagnetics (wave propagation) · Radio
science (waves in plasma) · Space plasma physics (active perturbation
experiments). |
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