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Recently Pop ({\it Solar Phys.} {\bf 276}, 351, 2012) identified a Laplace (or double exponential) distribution in the number of days with a given absolute value in the change over a day, in sunspot number, for days on which the sunspot…

Solar and Stellar Astrophysics · Physics 2015-06-11 Patrick L. Noble , Michael S. Wheatland

The McNish and Lincoln (ML) method, introduced in 1949, was one of the first attempts to produce mid-term forecasts of solar activity, up to 12 months ahead. However, it has been poorly described and evaluated in the past literature, in…

Solar and Stellar Astrophysics · Physics 2024-02-15 Frédéric Clette , Shantanu Jain , Tatiana Podladchikova

The sunspot activity is the end result of the cyclic destruction and regeneration of magnetic fields by the dynamo action. We propose a new method to analyze the daily sunspot areas data recorded since 1874. By computing the power spectral…

Solar and Stellar Astrophysics · Physics 2015-05-20 Ilidio Lopes , Hugo G. Silva

The Waldmeier Effect is the observation that the rise time of a sunspot cycle varies inversely with the cycle amplitude: strong cycles rise to their maximum faster than weak cycles. The shape of the cycle and thus the rise time does not…

Solar and Stellar Astrophysics · Physics 2020-11-04 Leif Svalgaard , David H. Hathaway

Maunder Minimum forms an archetype for the Grand minima, and detailed knowledge of its temporal development has important consequences for the solar dynamo theory dealing with long-term solar activity evolution. Here we reconsider the…

Solar and Stellar Astrophysics · Physics 2015-05-27 J. M. Vaquero , M. C. Gallego , I. G. Usoskin , G. A. Kovaltsov

We have measured the meridional motions of the magnetic elements in the Sun's surface layers since 1996 and find systematic and substantial variations. In general the meridional flow speed is fast at cycle minima and slow at cycle maxima.…

Solar and Stellar Astrophysics · Physics 2015-06-19 David H. Hathaway , Lisa Upton

Sunspots have been observed for over four centuries and the magnetic nature of sunspot cycles has been known for about a century; however, some of its underlying physics still remain elusive. It is known that the solar magnetic cycle…

Solar and Stellar Astrophysics · Physics 2024-11-26 Priyansh Jaswal , Chitradeep Saha , Dibyendu Nandy

A new formula for predicting solar cycles based on the current theoretical understanding of the solar cycle from flux transport dynamo is presented. Two important processes---fluctuations in the Babcock-Leighton mechanism and variations in…

Solar and Stellar Astrophysics · Physics 2019-08-07 Gopal Hazra , Arnab Rai Choudhuri

The dynamic activity of the Sun -- sustained by a magnetohydrodynamic dynamo mechanism working in its interior -- modulates the electromagnetic, particulate and radiative environment in space. While solar activity variations on short…

Solar and Stellar Astrophysics · Physics 2021-03-31 Dibyendu Nandy

In this study, we used two methods to investigate the periodic behavior of sunspot counts in four categories for the time period January 1986-October 2013. These categories include the counts from simple (A and B), medium (C), large (D, E,…

Solar and Stellar Astrophysics · Physics 2014-07-23 A. Kilcik , A. Ozguc , V. B. Yurchyshyn , J. P. Rozelot

Solar activity has significant impacts on human activities and health. One most commonly used measure of solar activity is the sunspot number. This paper compares three important non-deep learning models, four popular deep learning models,…

Solar and Stellar Astrophysics · Physics 2022-05-26 Yuchen Dang , Ziqi Chen , Heng Li , Hai Shu

Our knowledge of the long-term evolution of solar activity and of its primary modulation, the 11-year cycle, largely depends on a single direct observational record: the visual sunspot counts that retrace the last 4 centuries, since the…

Solar and Stellar Astrophysics · Physics 2023-01-06 Frédéric Clette , Leif Svalgaard , José M. Vaquero , Edward W. Cliver

In addition to the Gnevyshev-Ohl rule (GOR), the relation of the odd cycle with the subsequent even one in the 22-year Hale solar cycle was found. It is shown that 3 years before the 11-year minimum $m$, the value of the relative sunspot…

Solar and Stellar Astrophysics · Physics 2022-08-02 Yu. A. Nagovitsyn , V. G. Ivanov

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

The Maunder minimum (MM) of greatly reduced solar activity took place in 1645-1715, but the exact level of sunspot activity is uncertain as based, to a large extent, on historical generic statements of the absence of spots on the Sun. Here…

Solar and Stellar Astrophysics · Physics 2015-05-11 J. M. Vaquero , G. A. Kovaltsov , I. G. Usoskin , V. M. S. Carrasco , M. C. Gallego

A new prediction technique based on logarithmic values is proposed to predict the maximum amplitude (Rm) of a solar cycle from the preceding minimum aa geomagnetic index (aamin). The correlation between lnRm and lnaamin (r = 0.92) is…

Solar and Stellar Astrophysics · Physics 2011-10-28 Z. L. Du

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

One of the most striking aspects of the 11-year sunspot cycle is that there have been times in the past when some cycles went missing, a most well-known example of this being the Maunder minimum during 1645-1715. Analyses of cosmogenic…

Solar and Stellar Astrophysics · Physics 2014-04-09 Arnab Rai Choudhuri , Bidya Binay Karak

In this paper Fourier Transform and Wavelet Transform are applied in case of recent 300 years of sunspot numbers to explain the solar cycles. Here basically parallel study of Fourier and Wavelet analysis are done and we have observed that…

Computational Engineering, Finance, and Science · Computer Science 2013-12-11 Sabyasachi Mukhopadhyay , Debadatta Dash , Asish Mitra , Prasanta K. Panigrahi

A simple method to detect inconsistencies in low annual sunspot numbers based on the relationship between these values and the annual number of active days is described. The analysis allowed for the detection of problems in the annual…

Solar and Stellar Astrophysics · Physics 2015-06-03 J. M. Vaquero , R. M. Trigo , M. C. Gallego
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