Review
Astronomy & Astrophysics
Prantika Bhowmik, Jie Jiang, Lisa Upton, Alexandre Lemerle, Dibyendu Nandy
Summary: The dynamic activity of stars, such as the Sun, affects planetary space environments through various factors. Solar phenomena like flares and coronal mass ejections can cause hazardous space weather. The primary driver of solar activity is magnetic fields created by a mechanism called the magnetohydrodynamic dynamo. While the mechanism of solar cycles has been studied for a long time, predicting the strength of future sunspot cycles remains challenging. This review discusses observational constraints, recent physical insights, and advances in solar cycle predictions.
SPACE SCIENCE REVIEWS
(2023)
Article
Engineering, Aerospace
Esraa Zeki Mohammed, Hussain Salih Akbar, Saaduldeen Husain Shukri
Summary: Recording solar activity is crucial in understanding space weather. This study monitored and recorded sunspot data in Baghdad, Iraq for cycles 22, 23, and 24. The results were compared to international studies, confirming the reliability of the local records.
ADVANCES IN SPACE RESEARCH
(2022)
Article
Astronomy & Astrophysics
Benjamin L. Alterman, Justin C. Kasper, Robert J. Leamon, Scott W. McIntosh
Summary: By studying the relationship between solar wind helium-to-hydrogen abundance (A(He)) and the onset of solar cycle, it was found that A(He) increases prior to sunspot number minima and experiences rapid depletion and recovery directly before cycle onset. The concurrence of A(He) shutoff across solar wind speeds suggests independence from solar wind acceleration and possible driving mechanism below the photosphere. This phenomenon is likely related to the overlap of adjacent solar cycles and equatorial flux cancelation during solar minima.
Review
Astronomy & Astrophysics
Aimee Norton, Rachel Howe, Lisa Upton, Ilya Usoskin
Summary: This article describes the defining observations of the solar cycle and their constraints on the dynamo processes within the Sun. It covers topics such as sunspot numbers, active region flux ranges and lifetimes, bipolar magnetic region tilt angles, Hale and Joy's law, and various other aspects.
SPACE SCIENCE REVIEWS
(2023)
Article
Astronomy & Astrophysics
Aleix Espuna Fontcuberta, Anubhab Ghosh, Saikat Chatterjee, Dhrubaditya Mitra, Dibyendu Nandy
Summary: The Sun's activity, associated with the solar magnetic cycle, creates space weather which can disrupt technologies. Predicting the solar magnetic cycle is important for humanity. Machine-learning algorithms, especially Echo State Network (ESN), show promising results for solar-cycle forecasting.
Article
Astronomy & Astrophysics
Inigo Arregui
Summary: This paper presents a new method for predicting solar cycles using Bayesian inference to calculate the probability of the maximum amplitude. The method quantifies the impact of uncertainty and provides an assessment of the prediction quality.
Article
Astronomy & Astrophysics
Andrey G. Tlatov
Summary: The article presents the results of analyzing the geometric characteristics of sunspots based on data from the Kislovodsk and Royal Greenwich Observatories. It is found that sunspots generally have an ellipsoidal shape with the major axis elongated along longitude and a predominant slope to the equator, varying in the northern and southern hemispheres. Furthermore, a relationship between the shape of sunspots in the current cycle and the amplitude of the next cycle of activity is identified.
Article
Astronomy & Astrophysics
Peng-Xin Gao
Summary: Based on the Debrecen Photoheliographic Data (DPD) sunspot catalog, the cyclical behaviors of tilt angles of all sunspot groups (SGs) and SGs with angular separation constraint S > 2.5(?) in Solar Cycles (SCs) 21 - 23 are investigated. It is found that during SC 23, the cyclical behaviors of tilt angles are different from those of SCs 21 and 22. The findings indicate that the tilt angles of SGs show different patterns during different solar cycles, and their values depend on the phase of each cycle.
Article
Astronomy & Astrophysics
Bibhuti Kumar Jha, Aditya Priyadarshi, Sudip Mandal, Subhamoy Chatterjee, Dipankar Banerjee
Summary: The study analyzes the solar rotation profile using data from Kodaikanal Solar Observatory and finds that larger sunspots rotate slower than smaller ones. There was no variation in rotation rates between solar activity extremes (maxima and minima) observed in the analysis.
Article
Astronomy & Astrophysics
Soumitra Hazra, Victor Reville, Barbara Perri, Antoine Strugarek, Allan Sacha Brun, Eric Buchlin
Summary: The study demonstrates that using an AW-driven wind model can better reproduce the observed characteristics of solar wind, including the bimodality of slow and fast solar winds and the anticorrelation with coronal source temperature. There are significant differences in solar wind properties between the two models, with the AW-driven model showing better agreement with observational data.
ASTROPHYSICAL JOURNAL
(2021)
Article
Astronomy & Astrophysics
G. Zhou, H-Q He
Summary: The study investigates the field-aligned anisotropy of solar wind turbulence through simultaneous two-point correlation measurements from 2001 to 2017. Results show that the Taylor scale and correlation scale exhibit different behaviors in different field directions during different solar activity stages. There is a significant correlation between sunspot number and anisotropy of solar wind turbulence.
ASTROPHYSICAL JOURNAL LETTERS
(2021)
Article
Astronomy & Astrophysics
V. M. S. Carrasco, A. A. Pevtsov, J. M. Nogales, J. M. Vaquero
Summary: The complete dataset of sunspot drawings recorded at Sacramento Peak Observatory has been digitized, showing similar behavior to the International Sunspot Number with a relatively stable ratio observed during a specific period. This work marks the first step towards publishing the sunspot catalogue in digital format, with plans to include more information in future versions.
Article
Astronomy & Astrophysics
R. J. Booth
Summary: This paper replicates and enhances the method used by Leamon et al. to predict the terminator of solar cycles, but finds that their claim to have identified a mathematically robust signature of terminators in sunspot records is not well founded. The results are significantly sensitive to both the starting point of the data and the centralizing constant used to provide a meaningful Hilbert phase. Realistic parameter choices may push the predicted terminator back by about 2 years, which has implications for predictions of the magnitude of the next cycle.
Article
Astronomy & Astrophysics
Merlin M. Mendoza, Chia-Hsien Lin
Summary: Solar pores play an important role in the concentration, dissipation, and transportation of solar magnetic flux. This study focuses on the investigation of their horizontal movement and its correlation with observable quantities. Statistical analysis of 61 compact pores reveals a high correlation between the direction of movement and the direction of maximum magnetic pressure difference at the opposite sides of the pores' edges. However, further analysis using transfer entropy suggests no significant causal relationship between the direction of motion and the direction of maximum magnetic pressure difference.
ASTROPHYSICAL JOURNAL
(2023)
Article
Astronomy & Astrophysics
Sergio Bernabe, Gabriel Garcia, Victor M. S. Carrasco, Jose M. Vaquero
Summary: SunMap is a new open-source software designed to provide a free, simple, and versatile tool for scientists studying solar activity to generate solar synoptic maps.