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Journal articles on the topic 'Sunspot activity'

Author: Grafiati

Published: 5 June 2025

Last updated: 2 August 2025

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1

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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2

Buraba, V. "V. Sunspots." Transactions of the International Astronomical Union 19, no. 1 (1985): 71–78. http://dx.doi.org/10.1017/s0251107x00006143.

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Several proceedings of scientific meetings on sunspots appeared during the 1981-1984 period [The Physics of Sunsots, Cram and Thomas (eds.) 1981; see also reports of regional meetings, e.g.. Third European Solar Meeting, Oxford 1981; Nordic Astronomy Meeting, O. Hauge (ed.), Oslo 1983; 11th Regional Consultation on Solar Physics, L. Dezsö and B. Kalman (eds.), Debrecen 1983]. New interest in sunspots was aroused through observations of EUV sunspot spectra from space and was also inspired by the growing number of observations of starspots and other stellar activities [IAU Symposium No. 102, Sol

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3

Carrasco, V. M. S., A. J. P. Aparicio, T. Chatzistergos, et al. "Understanding Solar Activity after the Maunder Minimum: Sunspot Records by Rost and Alischer." Astrophysical Journal 968, no. 2 (2024): 65. http://dx.doi.org/10.3847/1538-4357/ad3fb9.

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Abstract The Maunder Minimum was a period with significantly reduced solar activity between 1645 and 1715, approximately. The transition between the low solar activity in the Maunder Minimum and the subsequent “normal” regime of solar activity was gradual. However, there are discrepancies in the solar activity level from sunspot number indices and solar activity proxies in that period. Among the contemporaneous observers, Johann L. Rost and Sebastian Alischer were two key sunspot observers to understand the solar activity in this transition just after the Maunder Minimum. We have revised all t

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4

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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Mohamed, Mostafa A., and Mohamed El-Sayed El-Mahdy. "Impact of sunspot activity on the rainfall patterns over Eastern Africa: a case study of Sudan and South Sudan." Journal of Water and Climate Change 12, no. 5 (2021): 2104–24. http://dx.doi.org/10.2166/wcc.2021.312.

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Abstract The relation between sunspots and rainfall patterns is still obscure in Africa, especially for Sudan and South Sudan. This research explores the response of rainfall to solar activity in eastern regions of Africa, with a case study in Sudan and South Sudan. Rainfall varies with time; therefore, skillful monitoring, predicting, and early warning of rainfall events is indispensable. Severe climatic events, such as droughts and floods, are critical factors in planning and managing all socioeconomic activities. Similar trends for the sunspot activity (sunspot number and sunspot groups) ch

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Lustig, G., and H. Wöhl. "Plasma Motions around Sunspots." International Astronomical Union Colloquium 141 (1993): 40–43. http://dx.doi.org/10.1017/s0252921100028736.

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AbstractMotions of large, stable sunspots – which are in some cases even recurrent – are determined using the Vacuum Tower Telescope (VTT) at Tenerife and sunspot drawings taken at the Kanzelhöhe Observatory in Austria. Around the sunspots fields of about 100 by 100 arcseconds are covered by a scanning spectrograph entrance slit in steps of one arcsecond every 15 seconds to determine the plasma velocities. The main aim is a determination of plasma and sunspot velocities within larger fields of activity and a search for special patterns of plasma flows, which reflect the well-known braking of t

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7

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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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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9

Zhao, Cui, Shangbin Yang, Tingmei Wang, et al. "An Automatic Approach for Grouping Sunspots and Calculating Relative Sunspot Number on SDO/HMI Continuum Images." Astronomical Journal 167, no. 2 (2024): 52. http://dx.doi.org/10.3847/1538-3881/ad11e2.

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Abstract The relative sunspot number is one of the major parameters for the study of long-term solar activity. The automatic calculation of the relative sunspot number is more stable and accurate as compared to manual methods. In this paper, we propose an algorithm that can detect sunspots, and divide them into groups to automatically calculate the relative sunspot number. Mathematical morphology was adopted to detect sunspots then group them. The data set used were the continuum images from SDO/HMI. The process was carried out on the overall HMI data available on the timespan from 2022 Januar

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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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Goshu, Belay Sitotaw. "Mapping solar variability of equatorial sunspots and plasma flows." Brazilian Journal of Science 3, no. 9 (2024): 49–64. http://dx.doi.org/10.14295/bjs.v3i9.638.

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This study investigated the variability of equatorial sunspots and plasma flows, focusing on the detailed dynamics of solar activity revealed by sunspot data analysis and magnetic field evolution. The goals were to investigate the relationship between sunspot numbers with differential rotation, meridional circulation, and magnetic induction using observational data and theoretical models. The methods included studying historical sunspot data from 1700 to the present and using time series decomposition to find trends, seasonality, and residuals. The evolution of the solar magnetic field was pre

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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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13

Amareswari, K., K. Sankarasubramanian, and B. Ravindra. "Century long study of sunspot activity using the Kodaikanal white-light data." Proceedings of the International Astronomical Union 13, S340 (2018): 173–74. http://dx.doi.org/10.1017/s1743921318001965.

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AbstractSunspots are the most obvious and high contrast observable feature of solar magnetic activity in the photosphere. The morphological and kinematic behavior of sunspots on the solar surface need to be studied over a long time period to understand solar magnetic activity. For this, it is important to understand the long term emergence patterns, and developments, decay of the sunspots on the solar surface over many cycles. The long time sequence of the Kodaikanal white-light images provide a consistent data set for this study. The digitized images were calibrated for relative plate density

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14

Jin, Chunlan, Guiping Zhou, Haisheng Ji, and Jingxiu Wang. "Are There Local Dynamos Acting in Sunspot Regions?" Astrophysical Journal 975, no. 1 (2024): 46. http://dx.doi.org/10.3847/1538-4357/ad7820.

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Abstract In solar physics, a long-unanswered question is whether or not there are local dynamos acting in sunspot regions. Here we report an observed pattern of magnetic evolution that makes the sunspots alive with ample complexity and energy. This anomalous pattern manifests as peculiar bipolar magnetic emergences (BMEs), exhibiting the following characteristics: (1) the BMEs persistently appear beyond the penumbra, encircling the sunspot in an end-to-end configuration; (2) each BME gradually grows and separates its two polarities along an arc trajectory centered on the sunspot; (3) a circula

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15

Gallego, M. C., A. J. P. Aparicio, V. M. S. Carrasco, and J. M. Vaquero. "Three Scattered Sunspot Records in the Archive of the Royal Astronomical Observatory of the Spanish Navy (1789–1790)." Research Notes of the AAS 7, no. 11 (2023): 235. http://dx.doi.org/10.3847/2515-5172/ad08c9.

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Abstract The recovery of records of past solar observations is crucial to understand the evolution of solar activity. In this context, three records of sunspot observations made at the Royal Observatory of the Spanish Navy in 1789 January and July, and 1790 June are shown in the present work. The aim of the observers who performed these sunspot observations was the discovery of intramercurial planets crossing the solar disk. For that reason, the observers only recorded round and dark spots and they may not have recorded all the sunspots that they observed. However, these records provide us wit

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Vicente, Montano, Pajigal Romeo, and Sobrejuanite Glenndon. "Dynamics in Crude Oil Prices: A Markov-Switching Autoregressive Approach Incorporating Sunspot Activity." INTERNATIONAL JOURNAL OF MULTIDISCIPLINARY RESEARCH AND ANALYSIS 07, no. 08 (2024): 3873–84. https://doi.org/10.5281/zenodo.13348620.

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This paper deals with the dynamic relationship between world crude oil prices and the activities of sunspots in a two-state Markov-Switching Autoregressive (MS-AR) model. The data set used was from February 1994 to May 2023, with crude oil prices and sunspot numbers as an exogenous variable. The MS-AR framework allows for regime-dependent behavior in the intercept and autoregressive coefficients and in the impact of solar activity on oil prices. The result distinguishes two regimes characterized by different degrees of persistence and sensitivity to solar activity. State 1 is highly persistent

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Zmuk, Berislav, and Hrvoje Josic. "Investigation of the sunspots and GDP nexus: The case of Balkan countries." Ekonomski anali 68, no. 237 (2023): 69–95. http://dx.doi.org/10.2298/eka2337069z.

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The phenomenon known as sunspots refers to regions of the Sun?s photosphere that are darker than their surroundings because their surface temperature is lower. The sunspot growth theory, however debatable, is one of the first explanations for economic development that explains how variations in the Sun?s activity affect the business cycle. Jevons developed the sunspot hypothesis in 1875. To reevaluate this notion, this research uses correlation and regression analysis to explore the relationship between sunspots and GDP in the context of 11 Balkan nations over the years 1960-2021. By extending

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Clette, Frédéric, José M. Vaquero, María Cruz Gallego, and Laure Lefèvre. "Sunspot and Group Number: Recent advances from historical data." Proceedings of the International Astronomical Union 14, A30 (2018): 156–59. http://dx.doi.org/10.1017/s174392131900396x.

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AbstractDue to its unique 400-year duration, the sunspot number is a central reference for understanding the long-term evolution of solar activity and its influence on the Earth environment and climate. Here, we outline current data recovery work. For the sunspot number, we find historical evidence of a disruption in the source observers occurring in 1947–48. For the sunpot group number, recent data confirm the clear southern predominance of sunspots during the Maunder Minimum, while the umbra-penumbra ratio is similar to other epochs. For the Dalton minimum, newly recovered historical observa

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Dong, Qianqian, Yunfei Yang, Song Feng, Wei Dai, Bo Liang, and Jianping Xiong. "Extraction of Sunspots from Chinese Sunspot Drawings Based on Semisupervised Learning." Astrophysical Journal 970, no. 2 (2024): 120. http://dx.doi.org/10.3847/1538-4357/ad4865.

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Abstract China has six observing stations, providing over 52,000 handwritten sunspot drawings from 1947–2016. The observing stations are the Purple Mountain Astronomical Observatory (PMO), Yunnan Astronomical Observatory (YNAO), Qingdao Observatory Station (QDOS), Sheshan Observatory Station (SSOS), Beijing Planetarium (BJP), and Nanjing University (NJU). In this paper, we propose a new cotraining semisupervised learning method combining a semantic segmentation method named dynamic mutual training (DMT) boundary-guided semantic segmentation (BGSeg), i.e., DMT_BGSeg, which makes full use of the

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Berdyugina, S. V., and I. G. Usoskin. "Persistent Active Longitudes in Sunspot Activity: Sun-as-a-Star Approach." Symposium - International Astronomical Union 219 (2004): 128–32. http://dx.doi.org/10.1017/s007418090018204x.

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Using a new Sun-as-a-star approach we analyze sunspot group data for the past 120 years and reveal that sunspots are formed preferably in two persistent migrating active longitudes 180° apart. Their migration is determined by changes of the mean latitude of sunspots and the surface differential rotation. The two active regions periodically alternate being the dominant region with a period of about 3.7 years similar to the “flip-flop” phenomenon known in starspot activity. The fact that the Sun shows the same pattern of magnetic activity as highly active stars strengthens the solar paradigm for

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RODRÍGUEZ, J. V., V. M. SANCHEZ CARRASCO, and I. RODRÍGUEZ-RODRÍGUEZ. "A TEXT-MINING-BASED SCIENTOMETRIC ANALYSIS OF SUNSPOT NUMBER PREDICTION." Kosmìčna nauka ì tehnologìâ 31, no. 3 (2025): 03–27. https://doi.org/10.15407/knit2025.03.003.

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The activity of the Sun is a substantial driver of both the terrestrial and space environments, making the study and prediction of solar activity and its cycles crucial. Predicting the sunspot number index (SN) is particularly important; this parameter, referring to the number of sunspots and sunspot groups on the Sun’s photosphere, is a critical indicator of solar activity. With solar storms adversely affecting power grids, satellite operations, and communication systems, the ability to predict SN with reasonable accuracy is exceptionally helpful. As a consequence, there has been growing acad

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Lundstedt, H., L. Liszka, R. Lundin, and R. Muscheler. "Long-term solar activity explored with wavelet methods." Annales Geophysicae 24, no. 2 (2006): 769–78. http://dx.doi.org/10.5194/angeo-24-769-2006.

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Abstract. 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. Scalograms showed the very long-term scales of 2300 years (Hallstat cycle), 900-1000 years, 400-500 years, and 200 years (de Vries cycle). Scalograms of a newly-constructed 14C production rate showed interesting solar modulation during the Maunder minimum. Multi-Resolution Analysis (MRA) revealed the modulation in detail, as well as peaks of solar activity not seen in the sun

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Siagian, Ruben Cornelius, Lulut Alfaris, Ghulab Nabi Ahmad, et al. "Relationship between Solar Flux and Sunspot Activity Using Several Regression Models." JURNAL ILMU FISIKA | UNIVERSITAS ANDALAS 15, no. 2 (2023): 146–65. http://dx.doi.org/10.25077/jif.15.2.146-165.2023.

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This study examines the correlation and prediction between sunspots and solar flux, two closely related factors associated with solar activity, covering the period from 2005 to 2022. The study utilizes a combination of linear regression analysis and the ARIMA prediction method to analyze the relationship between these factors and forecast their values. The analysis results reveal a significant positive correlation between sunspots and solar flux. Additionally, the ARIMA prediction method suggests that the SARIMA model can effectively forecast the values of both sunspots and solar flux for a 12

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Orzaru, C. M. "On the Dimension of the Solar Activity Attractor." Symposium - International Astronomical Union 157 (1993): 91–95. http://dx.doi.org/10.1017/s0074180900173929.

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The correlation dimension D(2) as a characteristic measure of the regular or chaotic behaviour of the solar dynamical system has been calculated. The algorithm suggested by Grassberger and Procaccia (1983) has been applied to time series of relative sunspot numbers and of areas of sunspots and faculae. In the first case, a correlation dimension D(2) ≃ 1.5 has been found; in the other two cases, the algorithm was not convergent, the results obtained being not relevant, due to the too short series of data available.

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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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Visser, Marcel E., and Juan José Sanz. "Solar activity affects avian timing of reproduction." Biology Letters 5, no. 6 (2009): 739–42. http://dx.doi.org/10.1098/rsbl.2009.0429.

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Avian timing of reproduction is strongly affected by ambient temperature. Here we show that there is an additional effect of sunspots on laying date, from five long-term population studies of great and blue tits ( Parus major and Cyanistes caeruleus ), demonstrating for the first time that solar activity not only has an effect on population numbers but that it also affects the timing of animal behaviour. This effect is statistically independent of ambient temperature. In years with few sunspots, birds initiate laying late while they are often early in years with many sunspots. The sunspot effe

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JAIN, RAJMAL, and S. C. TRIPATHY. "Correlation study between sunspot and rainfall in Udaipur subregion." MAUSAM 48, no. 3 (2021): 405–12. http://dx.doi.org/10.54302/mausam.v48i3.4272.

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ABSTRACT. The cross correlation among 102 years rainfall data in Udaipur subtropical region and sunspots show tpe influence of solar activity on the climatic conditions of Udaipur. The periodicity obtained using rainfall and other data sets. such as. water storage of Jaisamand lake and gauge measurements of two rivers. Jakham and Karmoi, are similar to the periodicity of sunspots, which indicates a relationship between rainfall and sunspot activity. A period of about 27% is found to deviate from normal rains in the form of flood. excess and deficit of rains in Udaipur sub-tropical region. The

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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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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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Alexander, William J. R., and William J. R. Emeritus. "Linkages between Solar Activity and Climatic Responses." Energy & Environment 16, no. 2 (2005): 239–53. http://dx.doi.org/10.1260/0958305053749462.

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Statistically significant 21-year periodicity is present concurrently in South African annual rainfall, river flow, flood peak maxima, groundwater levels, lake levels and the Southern Oscillation Index. This is directly related to the double sunspot cycle. The first years of the periodic sequences are characterised by sudden, regular and therefore predictable, reversals from sequences of well below average rainfall and river flow (droughts) that are suddenly broken by sequences of well above average events (floods). These reversals are directly related to corresponding six-fold increases in su

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Greenkorn, Robert A. "Analysis of Sunspot Activity Cycles." Solar Physics 255, no. 2 (2009): 301–23. http://dx.doi.org/10.1007/s11207-009-9331-z.

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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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Сыч, Роберт, and Robert Sych. "Waves and oscillations in sunspot atmosphere: a review." Solnechno-Zemnaya Fizika 1, no. 2 (2015): 3–21. http://dx.doi.org/10.12737/7487.

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The review focuses on recent experimental and theoretical studies of sources of oscillations in the sunspot atmosphere. The results of observations with ground-based and spaceborne instruments are presented. An important role of the cut-off frequency in forming the spatial distribution of narrowband sources of oscillations above sunspot is shown. The alternative techniques for studying the magnetic field structure by using helioseismological data are discussed. The dynamics of propagating wave fronts is studied by applying the pixelized wavelet filtering technique. The height analysis of oscil

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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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Tulasi Ram, S., P. V. S. Rama Rao, K. Niranjan, et al. "The role of post-sunset vertical drifts at the equator in predicting the onset of VHF scintillations during high and low sunspot activity years." Annales Geophysicae 24, no. 6 (2006): 1609–16. http://dx.doi.org/10.5194/angeo-24-1609-2006.

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Abstract. The day-to-day variability in the occurrence of ionospheric scintillations, which are of serious concern in the trans-ionospheric communications, makes their prediction still a challenging problem. This paper reports on a systematic study in quantitatively identifying the precursors responsible, such as pre-reversal E×B drift velocity, geo-magnetic activity index (Kp) and the Equatorial Ionization Anomaly (EIA) gradient, for the onset of VHF scintillations over a low-latitude station, Waltair (20° N dip), during high (2001) and low (2004) sunspot activity years. The percentage of occ

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Chen, Huirong, Song Liu, Ximing Yang, Xinggang Zhang, Jianzhong Yang, and Shaofen Fan. "Prediction of Sunspot Number with Hybrid Model Based on 1D-CNN, BiLSTM and Multi-Head Attention Mechanism." Electronics 13, no. 14 (2024): 2804. http://dx.doi.org/10.3390/electronics13142804.

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Sunspots have a significant impact on human activities. In this study, we aimed to improve solar activity prediction accuracy. To predict the sunspot number based on different aspects, such as extracted features and relationships among data, we developed a hybrid model that includes a one-dimensional convolutional neural network (1D-CNN) for extracting the features of sunspots and bidirectional long short-term memory (BiLSTM) embedded with a multi-head attention mechanism (MHAM) to learn the inner relationships among data and finally predict the sunspot number. We evaluated our model and sever

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Berisha, Arban. "Solar and Human Activity Impact on High and Low Land River Flows." Civil Engineering Journal 9, no. 7 (2023): 1630–45. http://dx.doi.org/10.28991/cej-2023-09-07-06.

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In the last two decades, in the Kosovo area, we have seen extraordinary climate changes and their consequences, such as flash floods, empty reservoirs, and forest burning. So, the objective of this article is to analyze the main drivers of climate change due to global warming, like Temperatures, Precipitation, River flows (TPQ), Human Activity (HA) on one side and the extraterritorial factor of sunspot number NS on the other side. The methodology of the approach is statistical, with trend detection, comparison, and calculation of significance for each factor. There are data in state institutio

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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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Yogihati, C. I., I. A. Shofi, and H. Heriyanto. "Analysis of Flare Occurring Based on Sunspot Changing Patterns Using Zurich Method in February – April 2022 at the Astronomy Laboratory of Physics FMIPA State University of Malang." Journal of Physics: Conference Series 2377, no. 1 (2022): 012036. http://dx.doi.org/10.1088/1742-6596/2377/1/012036.

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The star closest to our Earth is the sun with an average distance of 149,680,000 km. The sun is plasma with a very high temperature. The most easily observed solar activity from Earth are sunspots and flares, where flares on the sun can affect the Earth’s atmosphere. Therefore with this, research was carried out in February - April 2022 at the Laboratory of Astronomy Physics, State University of Malang with a geographical location of 07° 57’ 39” South Latitude, 112° 37’ 9.2” East Longitude, and 7.9607° North Latitude at an altitude of 465 meters with using the Celestron telescope. This study a

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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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Aparicio, A. J. P., and J. M. Vaquero. "A Comment on the Solar Activity Level in 1791 by Lorenzo Hervás y Panduro." Research Notes of the AAS 8, no. 6 (2024): 164. http://dx.doi.org/10.3847/2515-5172/ad5960.

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Abstract Past solar activity is of great interest for astrophysical and geophysical studies. Systematic searches over the last four centuries have detailed the evolution of the solar cycle. Brief comments on solar activity for periods with sparse records, such as the year 1791, are crucial. Lorenzo Hervás y Panduro, a Jesuit intellectual, noted in his 1793 book that sunspots were seen almost daily from 1791 January 1 to April 20. This would suggest a solar activity level estimated at a sunspot number of around 70.

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TANDON, J. N. "Solar Terrestrial Relationships." MAUSAM 14, no. 3 (2022): 302–14. http://dx.doi.org/10.54302/mausam.v14i3.5458.

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The identification of moderate geomagnetic activity with various solar regions has been discussed in the light of the long sequences of annual variation (30 to -50 solar rotations) obtained from the analysis of geomagnetic activity of the low sunspot activity periods 1920-24, 1930-34, 1940-44 (no long sequences) and 1950-54 and solar axial hypothesis. On the basis of these identifications it is shown that the geomagnetic activity can broadly be grouped in three heads-(l) Intense geomagnetic storms, (2) disturbed M -storms and (3) quiet M-storms.  Various features of these geomagnet

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Carrasco, V. M. S., M. C. Gallego, J. Villalba Álvarez, and J. M. Vaquero. "Sunspot observations by Charles Malapert during the period 1618–1626: a key data set to understand solar activity before the Maunder minimum." Monthly Notices of the Royal Astronomical Society 488, no. 3 (2019): 3884–95. http://dx.doi.org/10.1093/mnras/stz1867.

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ABSTRACT A revision is presented of the sunspot observations made by Charles Malapert from 1618 to 1626, studying several documentary sources that include those observations. The revised accounting of the group numbers recorded by Malapert for that period shows new information unavailable in the current sunspot group data base. The average solar activity level calculated from these revised records of Malapert is by almost one-third greater than that calculated from his records included in the current group data base. Comparison of the sunspot observations made by Malapert and by other astronom

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Tlatova, Kseniya A., Valeriya Vasil’eva, and Andrey Tlatov. "Reconstruction of solar activity according to the data of centenary observations." Proceedings of the International Astronomical Union 13, S340 (2018): 137–40. http://dx.doi.org/10.1017/s1743921318001473.

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AbstractDigitization of solar activity data over a period of more than 100 years has been performed. The database presents the characteristics of sunspots, sunspot umbras, filaments, plages in CaIIK line and prominences. The series of vector boundaries and photometric properties of the selected objects are created.The characteristics of individual types of solar activity were determined. An interactive atlas of solar activity has been created, on which daily maps of solar activity, characteristics of individual elements and summary indices of solar activity are presented. The indices of solar

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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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Yu, Ziyang, Xinpeng Yu, Yinuo Liu, Yue Li, Yuyan Zeng, and Yanqing Liu. "Prediction of Sunspot Activity Based on Differential Evolution Algorithm and BP Neural Network Model." Frontiers in Computing and Intelligent Systems 10, no. 2 (2024): 50–54. http://dx.doi.org/10.54097/562ea683.

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In this research report, the prediction method of sunspot activity is deeply discussed, and a variety of statistical and data science models are used to make comprehensive prediction. Research focuses include the start time and duration of the solar maximum in the solar cycle, as well as the prediction of the number and area of sunspots. By capturing the periodicity of solar activity, Pearson correlation coefficient is used to analyze the relationship between the maximum solar activity and the number of sunspots, and the adaptive multivariate nonlinear regression-BP neural network model and pa

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Summerhayes, Colin P. "Comment on ‘The Medieval Quiet Period’ – Implications arising from models of solar irradiance." Holocene 27, no. 2 (2016): 315–16. http://dx.doi.org/10.1177/0959683616658532.

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The recent re-evaluation of sunspot data by Clette et al. strongly suggests that the total solar irradiance (TSI) values for the late 20th century were (apart from 1960) not significantly different from those of the periods of sunspot maxima in the 1780s and the 1840s–1860s in the latter part of the ‘Little Ice Age’. In effect, the re-evaluation removed the previously supposed sunspot maximum of the ‘modern’ period. That means that the supposed recovery of TSI levels to values significantly higher in the late 20th century than those of the ‘Medieval Quiet (or Warm) Period’ (Figure 1 of Bradley

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Ahluwalia, H. S. "Forecast for sunspot cycle 25 activity." Advances in Space Research 69, no. 1 (2022): 794–97. http://dx.doi.org/10.1016/j.asr.2021.09.035.

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Bhattacharya, Atreyee. "Monsoons intensify with peak sunspot activity." Eos, Transactions American Geophysical Union 93, no. 38 (2012): 372. http://dx.doi.org/10.1029/2012eo380014.

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Li, K. J., P. X. Gao, L. S. Zhan, and X. J. Shi. "THE LONG-TERM HEMISPHERIC SUNSPOT ACTIVITY." Astrophysical Journal 691, no. 1 (2009): 75–82. http://dx.doi.org/10.1088/0004-637x/691/1/75.

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