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The problem of prediction of a given time series is examined on the basis of recent nonlinear dynamics theories. Particular attention is devoted to forecast the amplitude and phase of one of the most common solar indicator activity, the…

Data Analysis, Statistics and Probability · Physics 2007-05-23 Stefano Sello

We could infer a secular decreasing trend in the poloidal to toroidal solar magnetic flux amplification factor ( Af) using geomagnetic observations ( classic and IHV corrected aa indices) during the sunspot cycles 9-23. A similar decreasing…

General Physics · Physics 2010-12-23 T. E. Girish , G. Gopkumar

The use of the spotless days to predict the future solar activity is here revised based on the new version of the sunspot number index with a 24-month filter. Data from Solar Cycle (SC) 10 are considered because from this solar cycle the…

Solar and Stellar Astrophysics · Physics 2017-11-15 V. M. S. Carrasco , J. M. Vaquero , M. C. Gallego

It is shown that the description of the solar cycle that takes into account the odd zonal harmonic of the solar magnetic field allows us to deepen our knowledge of two important aspects of the solar activity. First, to clarify and expand…

Solar and Stellar Astrophysics · Physics 2023-11-02 V. N. Obridko , D. D. Sokoloff , M. M. Katsova

The solar magnetic field, thought to be generated by the motion of plasma within the Sun, alternates on the order of 11-year cycles and is incompletely understood. Industries rely on accurate forecasts of solar activity, but can solar…

Solar and Stellar Astrophysics · Physics 2025-02-20 Floe Foxon

Solar flares are the most explosive phenomena in the solar system and the main trigger of the events' chain that starts from Coronal Mass Ejections and leads to geomagnetic storms with possible impacts on the infrastructures at Earth.…

Solar and Stellar Astrophysics · Physics 2025-10-03 Chiara Curletto , Paolo Massa , Valeria Tagliafico , Cristina Campi , Federico Benvenuto , Michele Piana , Andrea Tacchino

We present a comprehensive analysis of Solar Cycle 25 aimed at precisely constraining the interval of its activity maximum using multiple observational parameters: sunspot number (SSN), Wolf number, the 10.7 cm solar radio flux (F10.7), the…

Solar and Stellar Astrophysics · Physics 2025-11-24 Homer Dávila Gutiérrez

Is Solar Cycle 24 anomalous? How do we predict the main features of a forthcoming cycle? In order to reply such questions, this work partitions quantitatively each cycle into valley, ascend, peak, and descend phases, statistically…

Solar and Stellar Astrophysics · Physics 2018-12-26 Baolin Tan

The solar activity in the current, that is, the 24-th, sunspot cycle is analyzed. Cyclic variations in the sunspot number (SSN) and radiation fluxes in various spectral ranges have been estimated in comparison with the general level of the…

Solar and Stellar Astrophysics · Physics 2018-05-01 E. A. Bruevich , V. V. Bruevich , G. V. Yakunina

This work continues our research of connection between the long-term activity of stars and their planets. We analyze new data on the previously considered two dozen solar-type stars with identified cycles, adding the results of studying the…

Solar and Stellar Astrophysics · Physics 2024-08-29 V. N. Obridko , M. M. Katsova , D. D. Sokoloff , N. V. Emelianov

We develop and discuss the properties of a new class of lattice-based avalanche models of solar flares. These models are readily amenable to a relatively unambiguous physical interpretation in terms of slow twisting of a coronal loop. They…

Solar and Stellar Astrophysics · Physics 2015-06-18 Antoine Strugarek , Paul Charbonneau , Richard Joseph , Dorian Pirot

The solar interior is probed by the properties of the Sun's acoustic oscillations (p-modes) observed on the solar surface. The frequencies of these p-modes measured in the last three decades show long term variation similar to the 11 year…

Solar and Stellar Astrophysics · Physics 2026-04-23 Rekha Jain , Akash Kumar , Sushanta C. Tripathy

We describe the defining observations of the solar cycle that provide constraints for the dynamo processes operating within the Sun. Specifically, we report on the following topics: historical sunspot numbers and revisions; active region…

Solar and Stellar Astrophysics · Physics 2023-09-29 Aimee Norton , Rachel Howe , Lisa Upton , Ilya Usoskin

Sunspot numbers form a comprehensive, long-duration proxy of solar activity and have been used numerous times to empirically investigate the properties of the solar cycle. A number of correlations have been discovered over the 24 cycles for…

Solar and Stellar Astrophysics · Physics 2015-06-11 Yaming Yu , David A. van Dyk , Vinay L. Kashyap , C. Alex Young

Forecasting future solar activity has become crucial in our modern world, where intense eruptive phenomena mostly occurring during solar maximum are likely to be strongly damaging to satellites and telecommunications. We present a 4D…

Solar and Stellar Astrophysics · Physics 2025-07-02 L. Jouve , C. P. Hung , A. S. Brun , S. Hazra , A. Fournier , O. Talagrand , B. Perri , A. Strugarek

Using a reconstruction of sunspot numbers stretching over multiple millennia, we analyze the statistics of the occurrence of grand minima and maxima and set new observational constraints on long-term solar and stellar dynamo models. We…

Astrophysics · Physics 2014-11-18 I. G. Usoskin , S. K. Solanki , G. A. Kovaltsov

Prediction of solar activity cycles is challenging because physical processes inside the Sun involve a broad range of multiscale dynamics that no model can reproduce and because the available observations are highly limited and cover mostly…

Solar and Stellar Astrophysics · Physics 2020-09-30 Irina N. Kitiashvili

Solar flare forecasting research using machine learning (ML) has focused on high resolution magnetogram data from the SDO/HMI era covering Solar Cycle 24 and the start of Solar Cycle 25, with some efforts looking back to SOHO/MDI for data…

Solar and Stellar Astrophysics · Physics 2023-08-30 Kiera van der Sande , Andrés Muñoz-Jaramillo , Subhamoy Chatterjee

The ability to predict the future behavior of solar activity has become of extreme importance due to its effect on the near Earth environment. Predictions of both the amplitude and timing of the next solar cycle will assist in estimating…

Solar and Stellar Astrophysics · Physics 2015-05-20 A. Ajabshirizadeh , N. Masoumzadeh Jouzdani , S. Abbassi

Solar flares are energetic events taking place in the Sun's atmosphere, and their effects can greatly impact the environment of the surrounding planets. In particular, eruptive flares, as opposed to confined flares, launch coronal mass…

Solar and Stellar Astrophysics · Physics 2016-01-20 Miho Janvier , Guillaume Aulanier , Pascal Demoulin