There is increasing interest in the
relation between the solar activity and climate change. Regarding the solar
activity, the fractal property of the sunspot number (SSN) has been studied by
many previous works. In general, fractal properties have been observed in the time
series of the dynamics of complex systems.
In this study, the
authors examined the relationship among the solar activity, total ozone, and
the North Atlantic Oscillation (NAO) from a viewpoint of multi-fractality and investigated
the change of multifractal behavior of the SSN, F10.7 flux, geomagnetic aa,
total ozone, NAO, the global temperature, and NH sea ice area indices by the
multifractal analysis using the wavelet transform. For this purpose, they also illustrated
the change of multifractality by plotting the τ-function and used the wavelet coherence.
The results showed
that the solar activity related to the NAO, by observing the matching in
monofractality or multifractality of these indices. When the SSN increased, the
solar activity became stable and the NAO also became stable. When the SSN
became maximum, the fractality of the SSN, F10.7 flux, geomagnetic aa, and NAO
indices changed from multifractality to monofractality and those states became
stable for most of the solar cycles. Also, an increase of a fluctuation was
observed in a coupled chaotic system just before chaos synchronization. When
the SSN became maximum, the fluctuations became large and multifractality
became strong, and a change from multifractal to monofractal behavior was
observed in the SSN, F10.7 flux, geomagnetic aa, and NAO indices. The strong
interactions of the solar flux, geomagnetic activity, total ozone, and NAO
occur in the SSN maximum. The strong interactions were inferred from the
similarity of fractality changes and the wavelet coherence. The influence of
the solar activity on the NAO was shown from a viewpoint of multi-fractality.
In short, these
findings will contribute to the research on the effects of the solar activity
on climate change.
Article by Fumio
Maruyama, et al, from Japan.
Full access: http://suo.im/4LEOAK
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