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| Titel |
Revised Dst and the epicycles of magnetic disturbance: 1958-2007 |
| VerfasserIn |
J. J. Love, J. L. Gannon |
| 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 (2009-08-11), S.3101-3131 |
| Datensatznummer |
250016617
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| Publikation (Nr.) |
 copernicus.org/angeo-27-3101-2009.pdf |
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| Zusammenfassung |
| A revised version of the storm-time disturbance index Dst is calculated
using hourly-mean magnetic-observatory data from four standard observatories
and collected over the years 1958–2007. The calculation algorithm is a
revision of that established by Sugiura et al., and which is now used by the
Kyoto World Data Center for routine production of Dst. The most important
new development is for the removal of solar-quiet variation. This is done
through time and frequency-domain band-stop filtering – selectively removing
specific Fourier terms approximating stationary periodic variation driven by
the Earth's rotation, the Moon's orbit, the Earth's orbit around the Sun, and
their mutual coupling. The resulting non-stationary disturbance time series
are weighted by observatory-site geomagnetic latitude and then averaged
together across longitudes to give what we call Dst5807-4SH. Comparisons are made with the standard Kyoto Dst. Various
biases, especially for residual solar-quiet variation, are identified in the
Kyoto Dst, and occasional storm-time errors in the Kyoto Dst are noted.
Using Dst5807-4SH, storms are ranked for maximum
storm-time intensity, and we show that storm-occurrence frequency follows a
power-law distribution with an exponential cutoff. The epicycles of magnetic
disturbance are explored: we (1) map low-latitude local-time disturbance
asymmetry, (2) confirm the 27-day storm-recurrence phenomenon using
autocorrelation, (3) investigate the coupled semi-annual-diurnal variation of
magnetic activity and the proposed explanatory equinoctial and
Russell-McPherron hypotheses, and (4) illustrate the well-known solar-cycle
modulation of storm-occurrence likelihood. Since Dst5807-4SH is useful for a variety of space physics and solid-Earth
applications, it is made freely available to the scientific community. |
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