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Revisiting the Sunspot Number [PDF]
Space Science Reviews, 2014 Our knowledge of the long-term evolution of solar activity and of its primary modulation, the 11-year cycle, largely depends on a single direct observational record: the visual sunspot counts that retrace the last 4 centuries, since the invention of the astronomical telescope.
Frédéric Clette +2 more
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Forecasting the number of sunspots for solar cycle 25 utilizing the facebook prophet model [PDF]
Scientific ReportsThe solar cycle, also referred to as the solar magnetic activity cycle, represents a nearly periodic change in solar activity occurring approximately every 11 years, as evidenced by the observation of sunspot numbers.
H. I. Abdel Rahman, W. A. Badawy
doaj +2 more sources
Journal of Space Weather and Space Climate, 2023 On a centennial timescale, solar activity oscillates quasi-periodically and also tends to occasionally get into a low-activity period. The Dalton Minimum (circa 1790s–1820s) was one of such low-activity periods that had been captured in telescopic ...
Hayakawa Hisashi +3 more
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The Ratio Between the Number of Sunspot and the Number of Sunspot Groups [PDF]
Geomagnetism and Aeronomy, 2017 Data from three solar observatories, Learmonth, Holloman, and San Vito, are used to study the variations in the average number of sunspots per sunspot group. It is found that the different types of sunspot groups and the number of sunspots in these groups have different solar cycle and cycle to cycle variations.
Georgieva, K. +3 more
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Relationship between group sunspot numbers and Wolf sunspot numbers [PDF]
Astronomische Nachrichten, 2010 AbstractContinuous wavelet transform and cross‐wavelet transform have been used to investigate the phase periodicity and synchrony of the monthly mean Wolf (Rz) and group (Rg) sunspot numbers during the period of June 1795 to December 1995. The Schwabe cycle is the only one common period in Rg and Rz, but it is not well‐defined in case of cycles 5–7 of
Li, Kejun, Liang, Hongfei
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Fractal Dimension and Maximum Sunspot Number in Solar Cycle [PDF]
Journal of Astronomy and Space Sciences, 2006 The fractal dimension is a quantitative parameter describing the characteristics of irregular time series. In this study, we use this parameter to analyze the irregular aspects of solar activity and to predict the maximum sunspot number in the following ...
R.-S. Kim +4 more
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Tests of Sunspot Number Sequences: 4. Discontinuities Around 1946 in Various Sunspot Number and Sunspot-Group-Number Reconstructions [PDF]
Solar Physics, 2016 In press with Solar ...
Lockwood, M., Owens, M. J., Barnard, L.
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Hemispheric sunspot numbers 1874–2020 [PDF]
Astronomy & Astrophysics, 2021 Context. Previous studies show significant north–south asymmetries for various features and indicators of solar activity. These findings suggest some decoupling between the two hemispheres over the solar cycle evolution, which is in agreement with dynamo theories.
Astrid M. Veronig +4 more
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Sunspot observations at Kawaguchi Science Museum: 1972 – 2013
Geoscience Data Journal, 2023 Individual sunspot observations have formed a ground basis of international sunspot number, a unique reference for long‐term solar variability in the centennial timescale.
Hisashi Hayakawa +5 more
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ANALYSIS OF SUNSPOT NUMBER FLUCTUATIONS [PDF]
Fractals, 2004 Monthly averages of the sunspot number visible on the sun, observed from 1749, Zurich Observatory, and from 1848 other observatories, have been analyzed. This time signal presents a frequency power spectra with a clear 1/fα behavior with α≃0.8±0.2.
Fanchiotti, H. +3 more
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