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We investigate the spatial and temporal variations of the high-degree mode frequencies calculated over localized regions of the Sun during the extended minimum phase between solar cycles 23 and 24. The frequency shifts measured relative to…

Solar and Stellar Astrophysics · Physics 2015-06-11 S. C. Tripathy , K. Jain , Frank Hill

We test recent claims that the polar field at the end of Cycle 23 was weakened by a small number of large, abnormally oriented regions, and investigate what this means for solar cycle prediction. We isolate the contribution of individual…

Solar and Stellar Astrophysics · Physics 2018-08-22 T. Whitbread , A. R. Yeates , A. Muñoz-Jaramillo

Data assimilation is a central problem in many geophysical applications, such as weather forecasting. It aims to estimate the state of a potentially large system, such as the atmosphere, from sparse observations, supplemented by prior…

Machine Learning · Computer Science 2024-06-24 Matthieu Blanke , Ronan Fablet , Marc Lelarge

We believe the Babcock--Leighton process of poloidal field generation to be the main source of irregularity in the solar cycle. The random nature of this process may make the poloidal field in one hemisphere stronger than that in the other…

Astrophysics · Physics 2009-02-09 Ashish Goel , Arnab Rai Choudhuri

The application of the Wavelet analysis and Fourier analysis to the dataset of variations of radiation fluxes of solar-like stars and the Sun is examined. In case of the Sun the wavelet-analysis helped us to see a set of values of periods…

Solar and Stellar Astrophysics · Physics 2012-04-06 E. A. Bruevich , I. K. Rozgacheva

Data Assimilation is the process in which we improve the representation of the state of a physical system by combining information coming from a numerical model, real-world observations, and some prior modelling. It is widely used to model…

Optimization and Control · Mathematics 2025-01-09 Victor Trappler , Arthur Vidard

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

The concept of degree of similarity ({\eta}) is proposed to quantitatively describe the similarity of a parameter (e.g. the maximum amplitude Rmax) of a solar cycle relative to a referenced one, and the prediction method of similar cycles…

Solar and Stellar Astrophysics · Physics 2015-06-03 Z. L. Du , H. N. Wang

Recently, Rozelot & Eren pointed out that the first solar gravitational moment (J2) might exhibit a temporal variation. The suggested explanation is through the temporal variation of the solar rotation with latitude. This issue is deeper…

Solar and Stellar Astrophysics · Physics 2023-01-19 Saliha Eren , Jean-Pierre Rozelot

The reconstruction and prediction of solar activity is one of the current problems in dynamo theory and global climate modeling. We estimate the Total Solar Irradiance for the next hundred years based on the Least Square Support Vector…

Solar and Stellar Astrophysics · Physics 2011-11-14 Victor Manuel Velasco Herrera , Blanca Mendoza , Graciela Velasco Herrera

We examine the solar-cycle variation of the power in the low-degree helioseismic modes by looking at binned power spectra from 45 years of observations with the Birmingham Solar Oscillations Network, which provides a more robust estimate of…

Solar and Stellar Astrophysics · Physics 2022-06-22 Rachel Howe , W. J. Chaplin , Y. P. Elsworth , S. J. Hale , M. B. Nielsen

Solar cycle is modeled as a forced and damped harmonic oscillator and the amplitudes, frequencies, phases and decay factors of such a harmonic oscillator are estimated by non-linear fitting the equation of sinusoidal and transient parts to…

Solar and Stellar Astrophysics · Physics 2022-04-12 K M Hiremath

Measurement of the solar wind speed near the Sun is important for understanding the acceleration mechanism of the solar wind. In this study, we determine 2D solar wind speeds from 6 to 26 solar radii by applying Fourier motion filters to…

Solar and Stellar Astrophysics · Physics 2018-08-29 Il-Hyun Cho , Yong-Jae Moon , Valery M. Nakariakov , Su-Chan Bong , Jin-Yi Lee , Donguk Song , Harim Lee , Kyung-Suk Cho

In this paper, we demonstrate the importance of embedding temporal information for an accurate prediction of solar irradiance. We have used two sets of models for forecasting solar irradiance. The first one uses only time series data of…

Solar and Stellar Astrophysics · Physics 2021-10-20 T. A. Fathima , Vasudevan Nedumpozhimana , Yee Hui Lee , Soumyabrata Dev

We study the asymmetric distribution of weak photospheric magnetic field values in the two hemispheres separately using synoptic maps from SDO/HMI, SOLIS/VSM and WSO during solar cycles 21-24. We calculate the weak-field asymmetry (shift)…

Solar and Stellar Astrophysics · Physics 2019-10-09 Tibebu Getachew , Ilpo Virtanen , Kalevi Mursula

Inter-cycle variations in the series of 11-year solar activity cycles have a significant impact on both the space environment and climate. Whether solar cycle variability is dominated by deterministic chaos or stochastic perturbations…

Solar and Stellar Astrophysics · Physics 2025-05-12 Zi-Fan Wang , Jie Jiang , Jing-Xiu Wang

We examine continuous measurements of the high-degree acoustic mode frequencies of the Sun covering the period from 2001 July to June 2014. These are obtained through the ring-diagram technique applied to the full-disk Doppler observations…

Solar and Stellar Astrophysics · Physics 2015-10-14 S. C. Tripathy , K. Jain , F. Hill

In recent years, the convergence of data-driven machine learning models with Data Assimilation (DA) offers a promising avenue for enhancing weather forecasting. This study delves into this emerging trend, presenting our methodologies and…

Atmospheric and Oceanic Physics · Physics 2024-01-17 Wenqi Wang , Jacob Bieker , Rossella Arcucci , César Quilodrán-Casas

Accurate prediction of solar activity calls for precise calibration of solar cycle models. Consequently we aim to find optimal parameters for models which describe the physical processes on the solar surface, which in turn act as proxies…

Solar and Stellar Astrophysics · Physics 2017-11-22 T. Whitbread , A. R. Yeates , A. Muñoz-Jaramillo , G. J. D. Petrie

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