Solar flare activity, 1937-2024: Introducing the New Hemispheric Solar flare index (hSFI) in the context of 2024's major Solar storm events
The result's identifiers
Result code in IS VaVaI
<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F67985815%3A_____%2F25%3A00642104" target="_blank" >RIV/67985815:_____/25:00642104 - isvavai.cz</a>
Result on the web
<a href="https://hdl.handle.net/11104/0372078" target="_blank" >https://hdl.handle.net/11104/0372078</a>
DOI - Digital Object Identifier
<a href="http://dx.doi.org/10.1029/2025SW004515" target="_blank" >10.1029/2025SW004515</a>
Alternative languages
Result language
angličtina
Original language name
Solar flare activity, 1937-2024: Introducing the New Hemispheric Solar flare index (hSFI) in the context of 2024's major Solar storm events
Original language description
A new daily composite of the solar flare index (SFI) and the hemispherically-resolved versions (hSFI) are presented for 1937 to 2024. The data set confirms that the northern hemisphere (NH) dominated solar flare activity during Solar Cycles 17 to 21, but that the southern hemisphere has dominated from Solar Cycle 22 to present. That said, the highest SFI value occurred in the NH during the recent superstorm of May 2024. In sunspot activity, the Gnevyshev-Ohl rule shows that the sum of sunspot numbers during even-numbered cycles is related to those of adjacent odd-numbered cycles. A similar rule appears to apply to SFI. The Gnevyshev gap phenomenon where solar maximum activity sometimes has two peaks separated by up to 1-2 years of a gap is confirmed for SFI. Although our data set represents the longest continuous daily data set for solar flare activity to-date, it is known that stronger solar flare events occurred before 1937. Therefore, a brief discussion of earlier solar flare events in the historical record is also provided for context. The statistics of the SFI and hSFI series are compared to other solar and geomagnetic activity indices, including the May and October 2024 solar storms. Statistical analysis of past geomagnetic storms confirms they are more frequent during active cycles and less frequent during solar minima. Strong geomagnetic storms are also more likely to occur during the positive phase of a 1.7 year's quasi-biennial oscillation in solar activity. The likelihood of low-magnetic latitude aurorae seems to have a 30 year periodicity component.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10308 - Astronomy (including astrophysics,space science)
Result continuities
Project
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Continuities
I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace
Others
Publication year
2025
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Space Weather-the International Journal of Research and Applications
ISSN
1542-7390
e-ISSN
1542-7390
Volume of the periodical
23
Issue of the periodical within the volume
11
Country of publishing house
US - UNITED STATES
Number of pages
37
Pages from-to
e2025SW004515
UT code for WoS article
001613580100001
EID of the result in the Scopus database
2-s2.0-105022015150