Trends of Solar, Interplanetary, and Geomagnetic Parameters during the Recent Five Solar Cycles
This study examined the variations of solar, interplanetary, and geomagnetic (SIG) parameters from 1974 to 2024 to assess the changes in the solar cycle. Eleven SIG parameters were analyzed, including the sunspot number (SSN), solar magnetic field, 10.7 cm solar radio flux, total solar irradiance,...
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| Main Authors: | , |
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| Format: | Article |
| Language: | English |
| Published: |
The Korean Space Science Society
2025-03-01
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| Series: | Journal of Astronomy and Space Sciences |
| Subjects: | |
| Online Access: | https://www.janss.kr/archive/view_article?pid=jass-42-1-29 |
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| Summary: | This study examined the variations of solar, interplanetary, and geomagnetic (SIG) parameters from 1974 to 2024 to assess
the changes in the solar cycle. Eleven SIG parameters were analyzed, including the sunspot number (SSN), solar magnetic
field, 10.7 cm solar radio flux, total solar irradiance, and Ap index. This study also aimed to predict Solar Cycle 25 using the
seasonal autoregressive integrated moving average (SARIMA) statistical forecasting model. The results showed that consistent
with previous studies, all SIG parameters exhibited a strong correlation with the SSN. The change in SSN strongly influences
the variations in all SIG parameters, even though some exhibit time-lagged responses. The cross-correlation analysis revealed
a high correlation coefficient of 0.9678 between the SSN and the 10.7 cm solar radio flux without delay. Most SIG parameters
showed a general weakening trend toward Solar Cycles 22–24. This suggests that solar activity is waning over time. In
particular, the solar polar magnetic field (SPMF) showed a large decrease in the solar minimum 23/24, and specifically, the
SPMF at the south pole weakened more rapidly than at the north pole. Hence, the SPMF is changing asymmetrically between
the north and south poles. This weakening of the solar magnetic field suggests an increase in galactic cosmic rays within the
heliosphere, exposing the Earth to higher levels of cosmic rays. Finally, forecasts for Solar Cycle 25 using the SARIMA model
predict that the SSN will continue to decline after the solar maximum in 2024, with the predicted minimum SSN of 9.42 in
October 2028, and will likely enter a solar minimum period around 2030. |
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| ISSN: | 2093-5587 2093-1409 |