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Titel |
The correlation between solar and geomagnetic activity – Part 3: An integral response model |
VerfasserIn |
Z. L. Du |
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. 6 ; Nr. 29, no. 6 (2011-06-15), S.1005-1018 |
Datensatznummer |
250017034
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Publikation (Nr.) |
copernicus.org/angeo-29-1005-2011.pdf |
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Zusammenfassung |
An integral response model is proposed to describe the
relationship between geomagnetic activity (aa index) and solar
activity (represented by sunspot number Rz): The aa
at a given time t is the integral of Rz at past
times (t'≤t) multiplied by an exponential decay factor of the
time differences (e−(t−t')/τ), where τ is the decay
time scale (~40 months). The correlation coefficient of aa
with the reconstructed series based on this model
(rf=0.85) is much higher than that of aa with
Rz (r0=0.61). If this model is applied to each
solar cycle, the correlation coefficient will be higher
(rf=0.95). This model can naturally explain some
phenomena related to aa and Rz, such as (i) the
significant increase in the aa index (and its baseline) over the
twentieth century; (ii) the longer lag times of aa to
Rz at solar cycle maxima than at minima; and (iii) the
variations in the correlations related to solar and Hale cycles.
These results demonstrate that aa depends not only on the
present Rz but also on past values. The profile of
aa can be better predicted from Rz by this model
than by point-point correspondence. |
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