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In the previous study (Hiremath 2006a), the solar cycle is modeled as a forced and damped harmonic oscillator and from all the 22 cycles (1755-1996), long-term amplitudes, frequencies, phases and decay factor are obtained. Using these…

Astrophysics · Physics 2007-05-23 K. M. Hiremath

The slopes of the linear relations between sunspot and white light (WL) facular areas at the onset of sunspot Cycles 12-21 correlate well with the amplitudes of those cycles between 1878-1980 (Brown and Evans, 1980). We use continuum images…

Solar and Stellar Astrophysics · Physics 2026-03-10 Peter Foukal

Total solar irradiance variations, about 0.1% between solar activity maximum and minimum, are available from accurate satellite measurements since 1978 and thus do not provide useful information on longer-term secular trends. Recently,…

Solar and Stellar Astrophysics · Physics 2012-05-23 S. Sello

We propose a simple method for prediction of the 11-year solar cycle maximum that is based on two relations. One of them is well known Waldmeier's rule that binds the amplitude of a cycle and the length of its ascending phase. The second…

Solar and Stellar Astrophysics · Physics 2022-08-03 Vladimir G. Ivanov

The Schwabe (~11 yr) value for the annual sunspot number is sometimes uncritically applied to other measures of solar activity, direct and indirect, including the 10.7 cm radio flux, the inflow of galactic cosmic rays, solar flare…

Solar and Stellar Astrophysics · Physics 2022-12-08 Claudio Vita-Finzi

A phenomenological model is presented for the quantitative description of individual solar cycles' features, such as onset, intensity, evolution, in terms of the number of M and X-class solar flares. The main elements of the model are the…

Solar and Stellar Astrophysics · Physics 2020-08-14 Eleni Petrakou

The Sun's polar magnetic fields are directly related to solar cycle variability. The strength of the polar fields at the start (minimum) of a cycle determine the subsequent amplitude of that cycle. In addition, the polar field reversals at…

Solar and Stellar Astrophysics · Physics 2014-08-01 Lisa Upton , David H. Hathaway

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

The difference between consecutive daily Sunspot Numbers was analysed. Its distribution was approximated on a large time scale with an exponential law. In order to verify this approximation a Maximum Entropy distribution was generated by a…

Solar and Stellar Astrophysics · Physics 2012-01-31 Mihail-Ioan Pop

The combined Greenwich and Solar Optical Observing Network (SOON) sunspot group data during 1874-2013 are analyzed and studied the relatively long-term variations in the annual sums of the areas of sunspot groups in 0-10 deg, 10-20 deg, and…

Solar and Stellar Astrophysics · Physics 2014-07-03 J. Javaraiah

The linear relationship between the maximum amplitudes (R$_{max}$) of sunspot cycles and preceding minima (R$_{min}$) is one of the precursor methods used to predict the amplitude of the upcoming solar cycle. In the recent past this method…

Solar and Stellar Astrophysics · Physics 2015-05-30 K. B. Ramesh , N. Bhagya Lakshmi

We investigate solar activity by focusing on double maxima in solar cycles and try to estimate the shape of the current solar cycle (Cycle 24) during its maximum. We analyzed data for Solar Cycle 24 by using Learmonth Solar Observatory…

Solar and Stellar Astrophysics · Physics 2013-09-04 Ali Kilcik , Atila Ozguc

One prominent feature of solar cycle is its irregular variation in its cycle strength, making it challenging to predict the amplitude of the next cycle. Studies show that fluctuations and nonlinearity in generating poloidal field throughout…

Solar and Stellar Astrophysics · Physics 2025-11-10 Bidisha Dey , Anu Sreedevi , Bidya Binay Karak

We present a hybrid forecasting strategy that combines numerical modeling, statistical forecasting, and machine learning methods to predict enhanced bursts of solar activity. These bursts, referred to here as space weather seasons, occur on…

Solar and Stellar Astrophysics · Physics 2026-05-27 Juie Shetye , Mausumi Dikpati

The short-term periodicities of the daily sunspot area fluctuations from August 1923 to October 1933 are discussed. For these data the correlative analysis indicates negative correlation for the periodicity of about 155 days, but the power…

Applications · Statistics 2010-09-17 Ryszarda Getko

Recently, using Greenwich and Solar Optical Observing Network sunspot group data during the period 1874-2006, (Javaraiah, MNRAS, 377, L34, 2007: Paper I), has found that: (1) the sum of the areas of the sunspot groups in 0-10 deg latitude…

Solar and Stellar Astrophysics · Physics 2011-08-31 J. Javaraiah

We have obtained empirical relations between the p-mode frequency shift and the change in solar activity indices. The empirical relations are determined on the basis of frequencies obtained from BBSO and GONG stations during solar cycle 22.…

Astrophysics · Physics 2015-06-24 Kiran Jain , S. C. Tripathy , A. Bhatnagar , B. Kumar

Solar activities have a great impact on modern high-tech systems, such as human aerospace, satellite communication and navigation, deep space exploration, and related scientific research. Therefore, studying the long - term evolution trend…

Solar and Stellar Astrophysics · Physics 2024-02-21 Peixin Luo , Baolin Tan

Having advanced knowledge of solar activity is important because the Sun's magnetic output governs space weather and impacts technologies reliant on space. However, the irregular nature of the solar cycle makes solar activity predictions a…

Solar and Stellar Astrophysics · Physics 2013-12-31 Dibyendu Nandy , Bidya Binay Karak

We analysed the combined data of sunspot groups from Greenwich Photoheliographic Results (GPR) during the period 1874-1976 and Debrecen Photoheliographic Data (DPD) during 1977-2017 and determined the monthly mean, annual mean, and 13-month…

Solar and Stellar Astrophysics · Physics 2024-05-07 J. Javaraiah