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| Titel |
Automatic detection of ionospheric Alfvén resonances using signal and image processing techniques |
| VerfasserIn |
C. D. Beggan |
| 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. 8 ; Nr. 32, no. 8 (2014-08-12), S.951-958 |
| Datensatznummer |
250121093
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| Publikation (Nr.) |
 copernicus.org/angeo-32-951-2014.pdf |
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| Zusammenfassung |
| Induction coils permit the measurement of small and very rapid changes of the
magnetic field. A new set of induction coils in the UK (at L = 3.2) record
magnetic field changes over an effective frequency range of 0.1–40 Hz,
encompassing phenomena such as the Schumann resonances, magnetospheric
pulsations and ionospheric Alfvén resonances (IARs). The IARs typically
manifest themselves as a series of spectral resonance structures (SRSs) within
the 1–10 Hz frequency range, usually appearing as fine bands or fringes in
spectrogram plots and occurring almost daily during local night-time,
disappearing during the daylight hours. The behaviour of the occurrence in
frequency (f) and the difference in frequency between fringes (Δf)
varies throughout the year. In order to quantify the daily, seasonal and
annual changes of the SRSs, we developed a new method based on signal and
image processing techniques to identify the fringes and to quantify the
values of f, Δf and other relevant parameters in the data set. The
technique is relatively robust to noise though requires tuning of threshold
parameters. We analyse 18 months of induction coil data to demonstrate
the utility of the method. |
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