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| Titel |
Secular trends in storm-level geomagnetic activity |
| VerfasserIn |
J. J. Love |
| 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 ; 29, no. 2 ; Nr. 29, no. 2 (2011-02-03), S.251-262 |
| Datensatznummer |
250016964
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| Publikation (Nr.) |
 copernicus.org/angeo-29-251-2011.pdf |
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| Zusammenfassung |
| Analysis is made of K-index data from groups of ground-based geomagnetic
observatories in Germany, Britain, and Australia, 1868.0–2009.0, solar cycles
11–23. Methods include nonparametric measures of trends and statistical
significance used by the hydrological and climatological research
communities. Among the three observatory groups, German K data
systematically record the highest disturbance levels, followed by the British
and, then, the Australian data. Signals consistently seen in K data from
all three observatory groups can be reasonably interpreted as physically
meaninginful: (1) geomagnetic activity has generally increased over the past
141 years. However, the detailed secular evolution of geomagnetic activity is
not well characterized by either a linear trend nor, even, a monotonic trend.
Therefore, simple, phenomenological extrapolations of past trends in solar
and geomagnetic activity levels are unlikely to be useful for making
quantitative predictions of future trends lasting longer than a solar cycle
or so. (2) The well-known tendency for magnetic storms to occur during the
declining phase of a sunspot-solar cycles is clearly seen for cycles 14–23;
it is not, however, clearly seen for cycles 11–13. Therefore, in addition to
an increase in geomagnetic activity, the nature of solar-terrestrial
interaction has also apparently changed over the past 141 years. |
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