Publication Date:
2023-10-31
Description:
The SYM-H and AE geomagnetic indices can be considered as proxies of the response of the Earth’s magnetosphere and ionosphere to solar magnetic activity. They indirectly monitor some electric current systems
which flow in the ionosphere and magnetosphere whose dynamics are directly or indirectly related to the Sun–
Earth interaction. Consequently, their temporal changes reflect processes occurring in the near-Earth space,
which contribute differently to the overall magnetosphere–ionosphere dynamics. The aim of this work is to
characterize the nature of these two geomagnetic indices by following a complex system approach and applying
a novel formalism, e.g., the EMD-based dominant amplitude multifractal formalism (EMD-DAMF). A set of
complexity measures, i.e., the Hurst exponent (H), the singularity width (𝛥𝛼) and the spectrum width (𝛥𝑓),
is evaluated for both geomagnetic indices analyzing data recorded during the last two solar cycles. One of
the most significant findings of this study is the absence of relevant differences between the two solar cycles
in terms of complexity measures for both geomagnetic indices, suggesting that only the occurrence and the
frequency of geomagnetic storms and substorms affect the Hurst exponent and the singularity widths of SYM-H
and AE indices. Moreover, while the AE index complexity measures do not show a significant dependence on
geomagnetic activity, the SYM-H index shows a reduction in its complexity features during the geomagnetic
storms, manifesting a more persistent behavior and moving from a (mono)fractal-like to a multifractal-like
behavior when passing from quiet to disturbed periods. Finally, our findings are consistent with previous
works on the forecast horizon of the geomagnetic activity as well as on the relation between the high-latitude
ionosphere and the low-latitude magnetosphere, thus confirming the importance of providing higher resolution
measures for correctly dealing with several Space Weather phenomena.
Description:
Published
Description:
105583
Description:
1A. Geomagnetismo e Paleomagnetismo
Description:
JCR Journal
Keywords:
near-Earth electromagnetic environment
;
Geomagnetic indices
;
Hilbert-Huang trasform
;
complexity measures
;
space weather
;
04.05. Geomagnetism
Repository Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Type:
article
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