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Journal articles on the topic 'Solar sunspot cycle'

Author: Grafiati

Published: 5 June 2025

Last updated: 15 July 2025

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1

Halder, Debojyoti. "Regression Analysis of Sunspot Numbers for the Solar Cycle 24 in Comparison to Previous Three Cycles." JOURNAL OF ADVANCES IN PHYSICS 4, no. 2 (2014): 477–83. http://dx.doi.org/10.24297/jap.v4i2.2030.

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Sunspots are temporary phenomena on the photosphere of the Sun which appear visibly as dark spots compared to surrounding regions. Sunspot populations usually rise fast but fall more slowly when observed for any particular solar cycle. The sunspot numbers for the current cycle 24 and the previous three cycles have been plotted for duration of first four years for each of them. It appears that the value of peak sunspot number for solar cycle 24 is smaller than the three preceding cycles. When regression analysis is made it exhibits a trend of slow rising phase of the cycle 24 compared to previo

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2

Ansor, N. M., N. I. Johari, Z. S. Hamidi, and N. N. M. Shariff. "Solar activity-climate relations during solar cycle 24." IOP Conference Series: Earth and Environmental Science 1151, no. 1 (2023): 012022. http://dx.doi.org/10.1088/1755-1315/1151/1/012022.

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Abstract Solar activity refers to every single Sun’s phenomenon, such as development of sunspots, solar flares, prominences etc. As determined by the number of sunspots, solar activity varies over an 11-year period. In this study, we examined the general distribution of thermosphere climate index (TCI) with respect to sunspot number during Solar Cycle 24 to obtain the pattern of thermal condition in thermosphere over the 11 years. Sunspot number, thermosphere climate index (TCI), mean temperature of surface air, and three latitudes, all obtained from NASA and NOAA, were used for this analysis.

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Norton, Aimee A., Eric H. Jones, Y. Liu, K. Hayashi, J. T. Hoeksema, and Jesper Schou. "How much more can sunspots tell us about the solar dynamo?" Proceedings of the International Astronomical Union 8, S294 (2012): 25–36. http://dx.doi.org/10.1017/s1743921313002172.

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AbstractSunspot observations inspired solar dynamo theory and continue to do so. Simply counting them established the sunspot cycle and its period. Latitudinal distributions introduced the tough constraint that the source of sunspots moves equator-ward as the cycle progresses. Observations of Hale's polarity law mandated hemispheric asymmetry. How much more can sunspots tell us about the solar dynamo? We draw attention to a few outstanding questions raised by inherent sunspot properties. Namely, how to explain sunspot rotation rates, the incoherence of follower spots, the longitudinal spacing

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4

Verma, S. D. "Tidal Force of Sun Due to Planetary Radial Alignment and Sun-Spot Cycle." International Astronomical Union Colloquium 132 (1993): 407–14. http://dx.doi.org/10.1017/s0252921100066306.

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AbstractIt is well known that the Sun’s radiation and a large number of phenomena occurring on the sun have influence on the Earth’s near environment i.e. Atmosphere, Ionosphere, Magnetosphere, etc. These manifest themselves as day-night, seasons, tides and many changes in the neutral atmosphere; changes in meteorological parameters. These changes are directly or indirectly related to variations in solar parameters, such as solar flares, magnetic storms, variations in sunspot number occurring in solar photosphere. Sunsports are observed, their number counted and their accurate records maintain

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Hayakawa, Hisashi, Koji Murata, E. Thomas H. Teague, Sabrina Bechet, and Mitsuru Sôma. "Analyses of Johannes Kepler’s Sunspot Drawings in 1607: A Revised Scenario for the Solar Cycles in the Early 17th Century." Astrophysical Journal Letters 970, no. 2 (2024): L31. http://dx.doi.org/10.3847/2041-8213/ad57c9.

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Abstract Telescopic sunspot observations began in 1610 and captured subsequent solar cycles. In combination with proxy reconstructions on an annual scale, these data sets indicate a gradual transition between regular solar cycles and the Maunder Minimum. The telescopic sunspot observations missed the beginning of the first telescopic solar cycle (Solar Cycle −13), leaving room for considerable uncertainty as to its temporal evolution. Before these early telescopic observations, however, Kepler made solar observations using camerae obscurae and recorded a sunspot group in three solar drawings i

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Takalo, Jouni, and Kalevi Mursula. "Comparison of the shape and temporal evolution of even and odd solar cycles." Astronomy & Astrophysics 636 (April 2020): A11. http://dx.doi.org/10.1051/0004-6361/202037488.

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Aims. We study the difference in the shape of solar cycles for even and odd cycles using the Wolf sunspot numbers and group sunspot numbers of solar cycles 1−23. We furthermore analyse the data of sunspot area sizes for even and odd cycles SC12−SC23 and sunspot group data for even and odd cycles SC8−SC23 to compare the temporal evolution of even and odd cycles. Methods. We applied the principal component analysis (PCA) to sunspot cycle data and studied the first two components, which describe the average cycle shape and cycle asymmetry. We used a distribution analysis to analyse the temporal e

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Meadows, P. J. "Remeasurement of Solar Observing Optical Network sunspot areas." Monthly Notices of the Royal Astronomical Society 497, no. 1 (2020): 1110–14. http://dx.doi.org/10.1093/mnras/staa2007.

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ABSTRACT The United States Air Force solar observing optical network (SOON) sunspot areas have been reported by several researchers over many years to be underestimated by as much as 50 per cent. Here, the areas of sunspots from scanned SOON disc drawings have been accurately remeasured for a period of two months from 2014 October and November – this being near the peak of Solar Cycle 24 and which includes the largest sunspot group of that cycle. The remeasured sunspot areas are now comparable with areas in sunspot catalogues.

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HASSAN, DANISH, MUHAMMAD FAHIM AKHTER, and SHAHEEN ABBAS. "THE SOLAR-TERRESTRIAL RELATIONSHIP USING FRACTAL DIMENSION." International Journal of Big Data Mining for Global Warming 02, no. 01 (2020): 2050002. http://dx.doi.org/10.1142/s2630534820500023.

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Sun is the main source of energy for the earth and other planets. Its activity in one or other way influences the terrestrial climate. Particularly, the solar activity manifested in the form of sunspots is found to be much more influential on the earth’s climate and on its magnetosphere. Links of the variability in terrestrial climate and sunspot cycles and associated magnetic cycles have been the concern of many recent studies. These two time series data sunspots and K-index are distributed into 22-year cycles, according to the magnetic field of the sun in which polarity reverses after 11-yea

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9

Xiang, N. B. "Revisiting the Question: The Cause of the Solar Cycle Variation of Total Solar Irradiance." Advances in Astronomy 2019 (March 26, 2019): 1–9. http://dx.doi.org/10.1155/2019/3641204.

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The Mg II index and sunspot area are usually used to represent the intensification contribution by solar bright structures to total solar irradiance (TSI) and sunspot darkening, respectively. In order to understand the cause of the solar cycle variation of TSI, we use extension of wavelet transform, wavelet coherence (WTC), and partial wavelet coherence (PWC), to revisit this issue. The WTC of TSI with sunspot area shows that the two time series are very coherent on timescales of one solar cycle, but the PWC of TSI with sunspot area, which can find the results of WTC after eliminating the effe

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Penza, Valentina, Francesco Berrilli, Luca Bertello, Matteo Cantoresi, and Serena Criscuoli. "Prediction of Sunspot and Plage Coverage for Solar Cycle 25." Astrophysical Journal Letters 922, no. 1 (2021): L12. http://dx.doi.org/10.3847/2041-8213/ac3663.

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Abstract Solar variability occurs over a broad range of spatial and temporal scales, from the Sun’s brightening over its lifetime to the fluctuations commonly associated with magnetic activity over minutes to years. The latter activity includes most prominently the 11 yr sunspot solar cycle and its modulations. Space weather events, in the form of solar flares, solar energetic particles, coronal mass ejections, and geomagnetic storms, have long been known to approximately follow the solar cycle occurring more frequently at solar maximum than solar minimum. These events can significantly impact

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H.I. Abdel Rahman. "Prediction of Sunspot Number During Solar Cycle 25: Deducing a New Model by Box-Jenkins Technique." Journal of Information Systems Engineering and Management 10, no. 50s (2025): 828–39. https://doi.org/10.52783/jisem.v10i50s.10400.

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Solar cycle is known as the solar magnetic activity cycle, is a nearly periodic 11 years change in the activity of the sun measured by observing the number of sunspots, its solar maximum and minimum refer to the periods of highest and lowest sunspot counts, respectively. Our recently studied cycle 25, which commenced in December 2019 with a minimum smoothed sunspot number of 1.8. It is expected to continue until around 2030. In our study, we developed a new statistical prediction model by using observed sunspot data from 1749 to August 2024 (approximately 276 years) to forecast sunspot numbers

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Penn, Matthew J., and William Livingston. "Long-term evolution of sunspot magnetic fields." Proceedings of the International Astronomical Union 6, S273 (2010): 126–33. http://dx.doi.org/10.1017/s1743921311015122.

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AbstractIndependent of the normal solar cycle, a decrease in the sunspot magnetic field strength has been observed using the Zeeman-split 1564.8nm Fe I spectral line at the NSO Kitt Peak McMath-Pierce telescope. Corresponding changes in sunspot brightness and the strength of molecular absorption lines were also seen. This trend was seen to continue in observations of the first sunspots of the new solar Cycle 24, and extrapolating a linear fit to this trend would lead to only half the number of spots in Cycle 24 compared to Cycle 23, and imply virtually no sunspots in Cycle 25.We examined synop

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Carrasco, V. M. S., J. M. Vaquero, and A. J. P. Aparicio. "Assessing the Evolution of Solar Cycle 25: A Weak-moderate Cycle." Research Notes of the AAS 8, no. 7 (2024): 183. http://dx.doi.org/10.3847/2515-5172/ad62fb.

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Abstract This note aims to analyze the evolution of the sunspot number for Solar Cycle 25, updating our previous findings on this topic. We compare daily, monthly and 13 months smoothed sunspot numbers for Solar Cycle 25 with those from previous cycles since mid-18th century (Solar Cycles 1–25). The highest daily, monthly and 13 months smoothed values for Solar Cycle 25 are significantly lower than the mean and median values considering all cycles. In particular, Solar Cycle 25 ranks 17th in terms of the highest 13 months smoothed sunspot number at this point in the cycle. Based on current dat

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SHAIKH, YUSUF H., A. R. KHAN, M. I. IQBAL, S. H. BEHERE, and S. P. BAGARE. "SUNSPOTS DATA ANALYSIS USING TIME SERIES." Fractals 16, no. 03 (2008): 259–65. http://dx.doi.org/10.1142/s0218348x08004009.

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The record of the sunspot number visible on the sun is regularly collected over the centuries by various observatories for studying the different factors influencing the sunspot cycle and solar activity. Sunspots appear in cycles, and last several years. These cycles follow a certain pattern which is well known. We analyzed monthly and yearly averages of sunspot data observed from year 1818 to 2002 using rescaled range analysis. The Hurst exponent calculated for monthly data sets are 0.8899, 0.8800 and 0.8597 and for yearly data set is 0.7187. Fractal dimensions1 calculated are 1.1100, 1.1200,

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Mishra, Wageesh, Nandita Srivastava, Yuming Wang, Zavkiddin Mirtoshev, Jie Zhang, and Rui Liu. "Mass loss via solar wind and coronal mass ejections during solar cycles 23 and 24." Monthly Notices of the Royal Astronomical Society 486, no. 4 (2019): 4671–85. http://dx.doi.org/10.1093/mnras/stz1001.

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ABSTRACT Similar to the Sun, other stars shed mass and magnetic flux via ubiquitous quasi-steady wind and episodic stellar coronal mass ejections (CMEs). We investigate the mass loss rate via solar wind and CMEs as a function of solar magnetic variability represented in terms of sunspot number and solar X-ray background luminosity. We estimate the contribution of CMEs to the total solar wind mass flux in the ecliptic and beyond, and its variation over different phases of the solar activity cycles. The study exploits the number of sunspots observed, coronagraphic observations of CMEs near the S

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RAYCHAUDHURI, PROBHAS. "TIME VARIATION OF SOLAR NEUTRINO FLUX." Modern Physics Letters A 08, no. 21 (1993): 1961–68. http://dx.doi.org/10.1142/s0217732393001677.

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Considering the solar neutrino data during the period from June, 1989 to April, 1992 within first sunspot maximum (it coincides with the maximum of the sunspot (Wolf numbers) and second sunspot maximum (usually appears 2–3 years after the first sunspot maximum) from the four solar neutrino experiments (37 Cl radiochemical, SAGE I & II, Gallex, Kamiokande II & III) we see that the average solar neutrino flux is much higher at the second sunspot maximum (May, 1991 to April, 1992) than at the first sunspot maximum (June, 1989 to April, 1991). This type of observation is already observed i

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17

Chandra, Y., B. Pande, M. C. Mathpal, and S. Pande. "N-S Asymmetry And Periodicity Of Daily Sunspot Number During Solar Cycles 22-24." Astrophysics 65, no. 3 (2022): 419–28. http://dx.doi.org/10.54503/0571-7132-2022.65.3-419.

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In this paper, a broad examination of the N-S asymmetry of daily sunspot numbers during the period January 1992 to March 2020 has been performed, examining its statistical significance and looking for the short term periodicity of daily sunspot numbers using the Fast Fourier Transform (FFT) during solar cycle 22 (1 January 1986 to 27 August 1996), cycle 23 (28 August 1996 to 10 December 2008) and cycle 24 (11 December 2008 to 31 March 2020). The present study indicates that sunspot number activity dominates in the southern hemisphere during the solar cycles 22 and 23, while during the solar cy

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Watson, Fraser, and Lyndsay Fletcher. "Automated sunspot detection and the evolution of sunspot magnetic fields during solar cycle 23." Proceedings of the International Astronomical Union 6, S273 (2010): 51–55. http://dx.doi.org/10.1017/s1743921311014992.

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AbstractThe automated detection of solar features is a technique which is relatively underused but if we are to keep up with the flow of data from spacecraft such as the recently launched Solar Dynamics Observatory, then such techniques will be very valuable to the solar community. Automated detection techniques allow us to examine a large set of data in a consistent way and in relatively short periods of time allowing for improved statistics to be carried out on any results obtained. This is particularly useful in the field of sunspot study as catalogues can be built with sunspots detected an

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Carrasco, V. M. S. "Number of Sunspot Groups and Individual Sunspots Recorded by Tevel for the Period 1816–1836 in the Dalton Minimum." Astrophysical Journal 922, no. 1 (2021): 58. http://dx.doi.org/10.3847/1538-4357/ac24a5.

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Abstract Cornelis Tevel made sunspot observations during the period 1816–1836, including the Dalton Minimum. In this work, the first revision of these observations since Wolf incorporated them into his database is presented. On the one hand, the number of individual sunspots from Tevel’s drawings was counted. This is of special interest for the sunspot number reconstruction because this kind of information is not as common in historical sunspot records as the number of groups. Thus, Tevel could be considered for the future reconstruction of the sunspot number index. On the other hand, the numb

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Echer, E., N. R. Rigozo, D. J. R. Nordemann, and L. E. A. Vieira. "Prediction of solar activity on the basis of spectral characteristics of sunspot number." Annales Geophysicae 22, no. 6 (2004): 2239–43. http://dx.doi.org/10.5194/angeo-22-2239-2004.

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Abstract. 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 iterative regression. The periods significant at the 95% confidence level were used in a sum of sine series to reconstruct sunspot series, to predict the strength of solar cycles 23 and 24. The maximum peak of solar cycles is adequately predicted (cycle 21: 158±13.2 against an observed peak of 155.4; cycle 22: 178

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Chang, Heon-Young. "Active Days around Solar Minimum and Solar Cycle Parameter." Journal of Astronomy and Space Sciences 38, no. 1 (2021): 23–29. http://dx.doi.org/10.5140/jass.2021.38.1.23.

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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 between the monthly sunspot numbers and the monthly number of active days in percentage (AD). As an effort of evaluating possibilities in use of the number of active days to predict solar activity, it is worthwhile to revisit and extend the analysis performed earlier. In calculating the Pearson’s linear correlation coefficient r, the Spearman’s rank-o

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Krasheninnikov, I. V., and S. O. Chumakov. "Predicting the Functional Dependence of the Sunspot Number in the Solar Activity Cycle Based on Elman Artificial Neural Network." Геомагнетизм и аэрономия 63, no. 2 (2023): 247–56. http://dx.doi.org/10.31857/s0016794022600612.

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The possibility of predicting the function of the time dependence of the sunspot number (SSN) inthe solar activity cycle is analyzed based on the application of the Elman artificial neural network platform tothe historical series of observational data. A method for normalizing the initial data for preliminary trainingof the ANN algorithm is proposed, in which a sequence of virtual idealized cycles is constructed using scaledduration coefficients and the amplitude of solar cycles. The correctness of the method is analyzed in a numericalexperiment based on modeling the time series of sunspots. T

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Gachari, Francis, David M. Mulati, and Joseph N. Mutuku. "Sunspot numbers: Implications on Eastern African rainfall." South African Journal of Science 110, no. 1/2 (2014): 1–5. http://dx.doi.org/10.1590/sajs.2014/20130050.

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Following NASA’s prediction of sunspot numbers for the current sunspot cycle, Cycle 24, we now include sunspot numbers as an explanatory variable in a statistical model. This model is based on fitting monthly rainfall values with factors and covariates obtained from solar–lunar geometry values and sunspot numbers. The model demonstrates high predictive skill in estimating monthly values by achieving a correlation coefficient of 0.9 between model estimates and the measurements. Estimates for monthly total rainfall for the period from 1901 to 2020 for Kenya indicate that the model can be used no

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Yazev, Sergey, Elena Isaeva, and Battulga Hos-Erdene. "Solar activity cycle 25: the first three years." Solar-Terrestrial Physics 9, no. 3 (2023): 3–9. http://dx.doi.org/10.12737/stp-93202301.

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We analyze features of current solar activity cycle 25 for the first three years of its development (2020–2022). Compared to cycle 24, the current cycle is shown to exceed the previous one in the number of sunspot groups (1.5 times), the number of flares (1.8 times), and the total flare index (1.5 times). We have found that distributions of sunspot groups during cycles 24 and 25 differ in maximum area. Solar cycle 25, unlike cycle 24, exhibits the most significant increase in the number of sunspot groups with areas up to 30 pmh and in the interval from 570 to 1000 pmh. In contrast to cycle 24,

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Ruzmaikin, A. A. "Order and Chaos in the Solar Cycle." Symposium - International Astronomical Union 138 (1990): 343–53. http://dx.doi.org/10.1017/s0074180900044326.

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Solar activity varying with an 11-year cycle is chaotic at large time scales. The evidence comes from an analysis of observations of the sunspot number and of radioactive carbon. Thereby an estimate of the dimension of the solar attractor can be obtained.The origin of the sunspots can be associated with the interactions of the regular, large-scale, chaotic, and intermittent magnetic fields.

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Kirov, Boian, Katya Georgieva, and Imeon Asenovski. "The Relationship Between Sunspot Numbers and Coronal Mass Ejections Within an 11-Year Solar Cycle." Revista de Gestão Social e Ambiental 19, no. 4 (2025): e011534. https://doi.org/10.24857/rgsa.v19n4-003.

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Objective: The objective of this study is to investigate the detailed relationship between the number of sunspots and the occurrence of coronal mass ejections within a complete eleven-year solar cycle, with the intention of elucidating the influence of various solar dynamo regimes on these phenomena. Theoretical Framework: This research is grounded in the flux transport dynamo theory, which explains the interplay between regimes dominated by advection and those dominated by diffusion. This framework provides a robust basis for understanding the observed double-peaked behavior of sunspot cycles

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Cao, Jie, Tingting Xu, Linhua Deng, et al. "An Improved Prediction of Solar Cycles 25 and 26 Using the Informer Model: Gnevyshev Peaks and North–South Asymmetry." Astrophysical Journal 969, no. 2 (2024): 120. http://dx.doi.org/10.3847/1538-4357/ad4551.

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Abstract Forecasting the amplitude and timing of the sunspot cycle is highly important for solar physics and space weather applications, but high-precision prediction of solar magnetic activity has remained an outstanding challenge. The Informer model, as the most advanced deep learning technique, is an ideal approach for predicting solar activity cycle. Using the whole-disk sunspot numbers (SSNs) between 1749 and 2023 and the hemispheric SSNs between 1992 and 2023, the amplitudes and timings of Solar Cycles 25 and 26 are predicted by the Informer model. The main results are the following: (1)

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Biswas, Akash. "The role of nonlinear toroidal flux loss due to flux emergence in the long-term evolution of the solar cycle." Proceedings of the International Astronomical Union 19, S365 (2023): 118–23. https://doi.org/10.1017/s1743921323005033.

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AbstractA striking feature of the solar cycle is that at the beginning, sunspots appear around mid-latitudes, and over time the latitudes of emergences migrate towards the equator. The maximum level of activity varies from cycle to cycle. For strong cycles, the activity begins early and at higher latitudes with wider sunspot distributions than for weak cycles. The activity and the width of sunspot belts increase rapidly and begin to decline when the belts are still at high latitudes. However, in the late stages of the cycles, the level of activity, and properties of the butterfly wings all hav

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Jiao, Qirong, Wenlong Liu, Dianjun Zhang, and Jinbin Cao. "Relation between Latitude-dependent Sunspot Data and Near-Earth Solar Wind Speed." Astrophysical Journal 958, no. 1 (2023): 70. http://dx.doi.org/10.3847/1538-4357/acfc21.

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Abstract Solar wind is important for the space environment between the Sun and the Earth and varies with the sunspot cycle, which is influenced by solar internal dynamics. We study the impact of latitude-dependent sunspot data on solar wind speed using the Granger causality test method and a machine-learning prediction approach. The results show that the low-latitude sunspot number has a larger effect on the solar wind speed. The time delay between the annual average solar wind speed and sunspot number decreases as the latitude range decreases. A machine-learning model is developed for the pre

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Pham Thi Thu, H., C. Amory-Mazaudier, and M. Le Huy. "Time variations of the ionosphere at the northern tropical crest of ionization at Phu Thuy, Vietnam." Annales Geophysicae 29, no. 1 (2011): 197–207. http://dx.doi.org/10.5194/angeo-29-197-2011.

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Abstract. This study is the first which gives the climatology of the ionosphere at the northern tropical crest of ionization in the Asian sector. We use the data from Phu Thuy station, in Vietnam, through three solar cycles (20, 21 and 22), showing the complete morphology of ionosphere parameters by analyzing long term variation, solar cycle variation and geomagnetic activity effects, seasonal evolution and diurnal development. Ionospheric critical frequencies, foF2, foF1 and foE, evolve according to the 11-year sunspot cycle. Seasonal variations show that foF2 exhibits a semiannual pattern wi

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Sarp, Volkan, and Ali Kılçık. "Nonlinear Prediction of Solar Cycle 25." Proceedings of the International Astronomical Union 13, S340 (2018): 321–22. http://dx.doi.org/10.1017/s1743921318001059.

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AbstractSolar activity is a chaotic process and there are various approximations to forecast its long term and short term variations. But there is no prediction method that predicts the solar activity exactly. In this study, a nonlinear prediction approach was applied to international sunspot numbers and performance of predictions was tested for the last 5 solar cycles. These predictions are in good agreement with observed values of the tested solar cycles. According to these results, end of cycle 24 is expected at February, 2020 with 7.7 smoothed monthly mean sunspot number and maximum of cyl

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Hazra, Soumitra, and Dibyendu Nandy. "The origin of parity changes in the solar cycle." Monthly Notices of the Royal Astronomical Society 489, no. 3 (2019): 4329–37. http://dx.doi.org/10.1093/mnras/stz2476.

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ABSTRACT Although sunspots have been systematically observed on the Sun’s surface over the last four centuries, their magnetic properties have been revealed and documented only since the early 1900s. Sunspots typically appear in pairs of opposite magnetic polarities which have a systematic orientation. This polarity orientation is opposite across the equator – a trend that has persisted over the last century. Taken together with the configuration of the global poloidal field of the Sun – this phenomena is consistent with the dipolar parity state of an underlying magnetohydrodynamic dynamo. Alt

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Hayakawa, Hisashi, Kentaro Hattori, Mitsuru Sôma, Tomoya Iju, Bruno P. Besser, and Shunsuke Kosaka. "An Overview of Sunspot Observations in 1727–1748." Astrophysical Journal 941, no. 2 (2022): 151. http://dx.doi.org/10.3847/1538-4357/ac6671.

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Abstract Solar activity generally exhibits cyclic behavior in terms of sunspot group number and sunspot positions every ≈11 yr. These sunspot data have therefore played key roles in numerous analyses of solar–terrestrial physics. However, their reconstructions prior to the 1830s have remained controversial and included significant data gaps, especially from the 1720s to the 1740s. Therefore, this study reviewed contemporary sunspot observations for 1727–1748 to add several forgotten records by Van Coesfelt in 1728–1729, Dûclos in 1736, Martin in 1737, and Cassini and Maraldi in 1748. On the ba

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Zhao, Heng, Hao Chen, and Linhao Qian. "Sunspot Prediction Based on The Adaptive ARIMA Model." Highlights in Science, Engineering and Technology 101 (May 20, 2024): 193–202. http://dx.doi.org/10.54097/xd3hne44.

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The sun is closely related to human beings, and any change in its activities may have a huge impact on human beings. The study and prediction of solar activities is particularly important for the survival and development of human beings. Humans often learn about solar activity by studying sunspots. In this paper, the study predicts the start time, end time, sunspot number, and area size of the next sunspot. In this paper, we predict the length and sunspot number and area of the next solar activity cycle based on the ARIMA time series model, the BP neural network model, and the trend model. In

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Yeo, K. L., S. K. Solanki, and N. A. Krivova. "How faculae and network relate to sunspots, and the implications for solar and stellar brightness variations." Astronomy & Astrophysics 639 (July 2020): A139. http://dx.doi.org/10.1051/0004-6361/202037739.

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Context. How global faculae and network coverage relates to that of sunspots is relevant to the brightness variations of the Sun and Sun-like stars. Aims. We aim to extend and improve on earlier studies that established that the facular-to-sunspot-area ratio diminishes with total sunspot coverage. Methods. Chromospheric indices and the total magnetic flux enclosed in network and faculae, referred to here as “facular indices”, are modulated by the amount of facular and network present. We probed the relationship between various facular and sunspot indices through an empirical model, taking into

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Zharkov, S. I., Elena Gavryuseva, and Valentyna V. Zharkova. "On phase relation between toroidal and poloidal magnetic fields in the solar cycle 23." Proceedings of the International Astronomical Union 3, S247 (2007): 39–45. http://dx.doi.org/10.1017/s1743921308014634.

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AbstractPhase relations is extracted at different latitudes between the weak background solar magnetic (poloidal) field and strong magnetic field associated with sunspots (toroidal field) by comparing low-resolution images from Wilcox Solar Observatory (WSO) and the high-resolution SOHO/MDI magnetograms. Sunspot areas and excess flux in all latitudinal zones (averaged with a sliding 1 year filter) reveal a strong positive correlation with the absolute and excess solar magnetic fields with a timelag of zero and ∼ 3 years. The residuals of a sunspot magnetic excess flux averaged by one year from

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Silbergleit, V. M. "Probable Values of Current Solar Cycle Peak." Advances in Astronomy 2012 (2012): 1–6. http://dx.doi.org/10.1155/2012/167375.

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An analysis of multiple linear regression method applied to solar cycles 4 to 23 using lagged values of smoothed monthly mean sunspot numbers as independent variables is presented. According to that, the amplitude of current solar cycle 24 is estimated providing a quantitative prediction result. Our adjustment shows that the current cycle would have a sunspot peak less than the biggest one observed during the cycle 19 giving an additional support to the declination in solar activity which is currently happening.

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Su, Xu, Bo Liang, Song Feng, Wei Dai, and Yunfei Yang. "Solar Cycle 25 Prediction Using N-BEATS." Astrophysical Journal 947, no. 2 (2023): 50. http://dx.doi.org/10.3847/1538-4357/acc799.

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Abstract Solar activities lead to Sun variation with an 11 yr periodicity. The periodic variation affects space weather and heliophysics research. So it is important to accurately predict solar cycle variations. In this paper, we predicted the ongoing Solar Cycle 25 using neural basis expansion analysis for the interpretable time series deep learning method. 13 months of smoothed monthly total sunspot numbers taken by sunspot Index and Long-term Solar Observations are selected to train and evaluate our model. We used root mean square error (RMSE) and mean absolute time lag (MATL) to evaluate o

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Veronig, Astrid M., Shantanu Jain, Tatiana Podladchikova, Werner Pötzi, and Frederic Clette. "Hemispheric sunspot numbers 1874–2020." Astronomy & Astrophysics 652 (August 2021): A56. http://dx.doi.org/10.1051/0004-6361/202141195.

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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. For the most important solar activity index, the sunspot numbers, so far only limited data are available for the two hemispheres independently. Aims. The aim of this study is to create a continuous series of daily and monthly hemispheric sunspot numbers (HSNs) from 1874 to 2020, which will be continuously expanded in the future with

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Peng, Yang, Yu Fei, Nan-bin Xiang, et al. "Statistical Comparison between Pores and Sunspots during the Time Interval 2010–2023." Astrophysical Journal 975, no. 1 (2024): 23. http://dx.doi.org/10.3847/1538-4357/ad7858.

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Abstract To reveal the physical properties of pores and sunspots varying with solar cycle, we carried out a statistical comparison among pores, transitional sunspots, and mature sunspots using Solar Dynamics Observatory/Helioseismic and Magnetic Imager from 2010 April to 2023 July. The OTSU method and region-growing algorithm were combined to detect umbrae of 11,876 sunspots covering solar cycles 24 and 25. The relationships between umbral area, continuum intensity (I), line-of-sight (LOS) magnetic field strength (B los), and line-of-sight velocity (V los) of umbrae were investigated in detail

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Bhatt, Nipa J., and Rajmal Jain. "Reassessing the Predictions of Sunspot Cycle 24." Proceedings of the International Astronomical Union 13, S340 (2018): 319–20. http://dx.doi.org/10.1017/s1743921318001205.

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AbstractPredictions of sunspot cycle are important due to their space weather effects. Bhattet al.(2009) predicted sunspot cycle 24 (Maximum amplitude: 92.8±19.6; Timing:October 2012±4 months) using relative sunspot number (International Sunspot Number), and average geomagnetic activity indexaaconsidering 2008 as the year of sunspot minimum. Owing to the extended solar minimum till 2009, we re-examine our prediction model. Also, the newly calibrated international sunspot number reduces many discrepancies in the old dataset and is available from Solar Influences Data Center (SIDC) website. Cons

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Kane, R. P. "Gnevyshev peaks in solar radio emissions at different frequencies." Annales Geophysicae 27, no. 4 (2009): 1469–75. http://dx.doi.org/10.5194/angeo-27-1469-2009.

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Abstract. Sunspots have a major 11-year cycle, but the years near the sunspot maximum show two or more peaks called GP (Gnevyshev Peaks). In this communication, it was examined whether these peaks in sunspots are reflected in other parameters such as Lyman-α (the chromospheric emission 121.6 nm), radio emissions 242–15 400 MHz emanating from altitude levels 2000–12 000 km, the low latitude (+45° to −45°) solar open magnetic flux and the coronal green line emission (Fe XIV, 530.3 nm). In the different solar cycles 20–23, the similarity extended at least upto the level of 609 MHz, but in cycle 2

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G Giovanelli, Ronald. "The Sunspot Cycle and Solar Magnetic Fields. I. The Mechanism as Inferred from Observation." Australian Journal of Physics 38, no. 6 (1985): 1045. http://dx.doi.org/10.1071/ph851045.

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Observations of solar magnetic and velocity fields can be used to derive the course of events involved in the solar cycle. These differ in three important respects from those of conventional dynamo theories: (i) Polar field reversal. Following the outbreak of a new cycle, magnetic flux released by sunspots diffuses initially by Leighton's random-walk process, but this is soon dominated by the observed poleward flow of about 20 m s - 1 which carries flux to polar regions in about 12 months. Since follower spots lie about 2� higher in latitude than leaders, follower flux arrives in polar regions

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Bravo, S., J. A. L. Cruz-Abeyro, and D. Rojas. "The spatial relationship between active regions and coronal holes and the occurrence of intense geomagnetic storms throughout the solar activity cycle." Annales Geophysicae 16, no. 1 (1998): 49–54. http://dx.doi.org/10.1007/s00585-997-0049-7.

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Abstract. We study the annual frequency of occurrence of intense geomagnetic storms (Dst < –100 nT) throughout the solar activity cycle for the last three cycles and find that it shows different structures. In cycles 20 and 22 it peaks during the ascending phase, near sunspot maximum. During cycle 21, however, there is one peak in the ascending phase and a second, higher, peak in the descending phase separated by a minimum of storm occurrence during 1980, the sunspot maximum. We compare the solar cycle distribution of storms with the corresponding evolution of coronal mass ejections and fla

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Ogurtsov, Maxim, and Markus Lindholm. "Statistical Effects in the Solar Activity Cycles during AD 1823–1996." ISRN Astronomy and Astrophysics 2011 (April 26, 2011): 1–7. http://dx.doi.org/10.5402/2011/640817.

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General statistical properties of solar activity cycles during the period AD 1823–1996—including the Gnevyshev-Ohl and Waldmeier effects as well as an amplitude-period effect—were analyzed using Wolf number, group sunspot number, and extended total sunspot area series. It was found out that the Gnevyshev-Ohl effect GO2 (the positive correlation between intensity of the even cycles 2N and intensity of the odd cycles 2N+1) and the Waldmeier effect W2 (the anticorrelation between rise times of sunspot cycles and their amplitudes) are the most universal and robust features of the solar cycle. Othe

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Das, Ratul, Aparup Ghosh, and Bidya Binay Karak. "Is the hemispheric asymmetry of sunspot cycle caused by an irregular process with long-term memory?" Monthly Notices of the Royal Astronomical Society 511, no. 1 (2022): 472–79. http://dx.doi.org/10.1093/mnras/stac035.

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ABSTRACT The hemispheric asymmetry of the sunspot cycle is a real feature of the Sun. However, its origin is still not well understood. Here, we perform nonlinear time series analysis of the sunspot area and number asymmetry to explore its dynamics. By measuring the correlation dimension of the sunspot asymmetry, we conclude that there is no strange attractor in the data. Further computing Higuchi’s dimension, we conclude that the hemispheric asymmetry is largely governed by stochastic noise. However, the behaviour of Hurst exponent reveals that the time series is not completely determined by

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Tlatov, Andrey G., and Vladimir N. Obridko. "Global magnetic fields: variation of solar minima." Proceedings of the International Astronomical Union 7, S286 (2011): 113–22. http://dx.doi.org/10.1017/s1743921312004723.

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AbstractThe topology of the large-scale magnetic field of the Sun and its role in the development of magnetic activity were investigated using Hα charts of the Sun in the period 1887-2011. We have considered the indices characterizing the minimum activity epoch, according to the data of large-scale magnetic fields. Such indices include: dipole-octopole index, area and average latitude of the field with dominant polarity in each hemisphere and others. We studied the correlation between these indices and the amplitude of the following sunspot cycle, and the relation between the duration of the c

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Singh, A. K., and A. Bhargawa. "ESTABLISHING SOLAR ACTIVITY TREND FOR SOLAR CYCLES 21 – 24." PHYSICS OF AURORAL PHENOMENA 44 (2021): 100–106. http://dx.doi.org/10.51981/2588-0039.2021.44.023.

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Solar-terrestrial environment is manifested primarily by the physical conditions of solar interior, solar atmosphere and eruptive solar plasma. Each parameter gives unique information about the Sun and its activity according to its defined characteristics. Hence the variability of solar parameters is of interest from the point of view of plasma dynamics on the Sun and in the interplanetary space as well as for the solar-terrestrial physics. In this study, we have analysed various solar transients and parameters to establish the recent trends of solar activity during solar cycles 21, 22, 23 and

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Carrasco, V. M. S., A. Muñoz-Jaramillo, M. C. Gallego, and J. M. Vaquero. "Revisiting Christoph Scheiner’s Sunspot Records: A New Perspective on Solar Activity of the Early Telescopic Era." Astrophysical Journal 927, no. 2 (2022): 193. http://dx.doi.org/10.3847/1538-4357/ac52ee.

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Abstract Christoph Scheiner was one of the most outstanding astronomers in the history of sunspot observations. His book, Rosa Ursina, is the reference work regarding the study of the earliest sunspot records. The sunspot observations compiled by Scheiner in Rosa Ursina and Prodomus, including records made by other observers, forms one of the main references of the observations known for that period—particularly around the 1620s. Thus, his work is crucial to determine the solar activity level of the first solar cycles of the telescopic era. The number of sunspot groups recorded in Scheiner’s d

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Yazev, Sergey, Elena Isaeva, and Battulga Hos-Erdene. "Solar activity cycle 25: the first three years." Solnechno-Zemnaya Fizika 9, no. 3 (2023): 5–11. http://dx.doi.org/10.12737/szf-93202301.

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We analyze features of current solar activity cycle 25 for the first three years of its development (2020–2022). Compared to cycle 24, the current cycle is shown to exceed the previous one in the number of sunspot groups (1.5 times), the number of flares (1.8 times), and the total flare index (1.5 times). We have found that distributions of sunspot groups during cycles 24 and 25 differ in maximum area. Solar cycle 25, unlike cycle 24, exhibits the most significant increase in the number of sunspot groups with areas up to 30 pmh and in the interval from 570 to 1000 pmh. In contrast to cycle 24,

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