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An Overview of Sunspot Observations in the Early Maunder Minimum: 1645 – 1659
, 2023 Hayakawa et al. (2024) derived sunspot group number and individual sunspot number in the early Maunder Minimum. See their details in Hayakawa et al.
早川, 尚志, Hayakawa, Hisashi
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A Representation of the Sunspot Cycle* [PDF]
Bell System Technical Journal, 1939 ALTHOUGH sunspots had been observed occasionally back to ancient times, their study may be said to date from their rediscovery by Galileo in the spring of 1610 with the then newly invented telescope. Since then much has been written about their nature, their periodicities and possible influence on human affairs.
openaire +3 more sources
Prediction of solar activity on the basis of spectral characteristics of sunspot number [PDF]
Annales Geophysicae, 2004 Prediction of solar activity strength for solar cycles 23 and 24 is performed on the basis of extrapolation of sunspot number spectral components. Sunspot number data during 1933-1996 periods (solar cycles 17-22) are searched for periodicities by ...
E. Echer +4 more
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Heartbeat of the sun from principal component analysis and prediction of solar activity on a millenium timescale [PDF]
, 2015 We derive two principal components (PCs) of temporal magnetic field variations over the solar cycles 21-24 from full disk magnetograms covering about 39% of data variance, with σ = 0.67. These PCs are attributed to two main magnetic waves travelling from
Shepherd, Simon J. +10 more
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Differential Rotation for Different-sized Sunspot Groups Early Observed by the OGAUC
The Astrophysical Journal, 2023 Solar differential rotation is an important ingredient of the solar dynamo model, not only because the solar rotation profile is one of the key inputs in a solar dynamo model, but also because it imposes constraints for the solar dynamo model.
Miao Wan +3 more
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Chromospheric seismology above sunspot umbrae [PDF]
, 2015 Context: The acoustic resonator is an important model for explaining the three-minute oscillations in the chromosphere above sunspot umbrae. The steep temperature gradients at the photosphere and transition region provide the cavity for the acoustic ...
G. J. J. Botha +5 more
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, 2021 A 93-year long cycle seems to be lurking in the solar sunspot activity ...
Cusmariu, Adolf
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Overlapping Magnetic Activity Cycles and the Sunspot Number: Forecasting Sunspot Cycle 25 Amplitude [PDF]
, 2020 The Sun exhibits a well-observed modulation in the number of spots on its disk over a period of about 11 years. From the dawn of modern observational astronomy, sunspots have presented a challenge to understanding—their quasi-periodic variation in number,
McIntosh, Scott W. +4 more
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Active Days around Solar Minimum and Solar Cycle Parameter
Journal of Astronomy and Space Sciences, 2021 Utilizing a new version of the sunspot number and group sunspot number dataset available since 2015, we have statistically studied the relationship between solar activity parameters describing solar cycles and the slope of the linear relationship ...
Heon-Young Chang
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Long-term solar activity explored with wavelet methods [PDF]
Annales Geophysicae, 2006 Long-term solar activity has been studied with a set of wavelet methods. The following indicators of long-term solar activity were used; the group sunspot number, the sunspot number, and the 14C production rate.
H. Lundstedt +3 more
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