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Solar active regions (ARs) determine solar polar fields and cause solar cycle variability within the framework of the Babcock-Leighton (BL) dynamo. The contribution of an AR to the polar field is measured by its dipole field, which results…

Solar and Stellar Astrophysics · Physics 2025-06-03 Ruihui Wang , Jie Jiang , Yukun Luo

Solar variability occurs over a broad range of spatial and temporal scales, from the Sun's brightening over its lifetime to the fluctuations commonly associated with magnetic activity over minutes to years. The latter activity includes most…

Solar and Stellar Astrophysics · Physics 2021-11-24 Valentina Penza , Francesco Berrilli , Luca Bertello , Matteo Cantoresi , Serena Criscuoli

Despite the known general properties of the solar cycles, a reliable forecast of the 11-year sunspot number variations is still a problem. The difficulties are caused by the apparent chaotic behavior of the sunspot numbers from cycle to…

Astrophysics · Physics 2009-11-13 I. N. Kitiashvili , A. G. Kosovichev

A striking feature of the solar cycle is that at the beginning, sunspots appear around mid-latitudes, and over time the latitudes of emergences migrate towards the equator. The maximum level of activity varies from cycle to cycle. For…

Solar and Stellar Astrophysics · Physics 2024-12-25 Akash Biswas

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

The subsurface meridional flow has long been recognized as a critical factor in driving the solar cycle. Specifically, the equatorward return flow in the tachocline is widely believed to be responsible for the formation of the sunspot…

Solar and Stellar Astrophysics · Physics 2025-08-20 Jie Jiang , Zebin Zhang

The magnetic activity of the Sun, as manifested in the sunspot cycle, originates deep within its convection zone through a dynamo mechanism which involves non-trivial interactions between the plasma and magnetic field in the solar interior.…

Solar and Stellar Astrophysics · Physics 2015-05-13 Dibyendu Nandy

Over the past century, the Sun's activity -- which exhibits significant variations -- went through a phase known as the Modern Maximum. Notably, the strongest sunspot cycle on record during this period, and indeed since direct sunspot…

Solar and Stellar Astrophysics · Physics 2025-08-20 Shaonwita Pal , Dibyendu Nandy

In 1969 Leighton developed a quasi-1D mathematical model of the solar dynamo, building upon the phenomenological scenario of Babcock(1961). Here we present a modification and extension of Leighton's model. Using the axisymmetric component…

Solar and Stellar Astrophysics · Physics 2017-03-01 R. H. Cameron , M. Schuessler

Using Greenwich and SOON sunspot group data during the period 1874 -- 2005, we find that the sums of the areas of the sunspot groups in $0^\circ$ -- $10^\circ$ latitude-interval of the Sun's northern hemisphere and in the time-interval,…

Astrophysics · Physics 2008-11-26 J. Javaraiah

It is known that the tilt angles of active regions increase with their latitude (Joy's law). It has never been checked before, however, whether the average tilt angles change from one cycle to another. Flux transport models show the…

Solar and Stellar Astrophysics · Physics 2015-05-18 Maria Dasi-Espuig , Sami K. Solanki , Natasha A. Krivova , Robert H. Cameron , Tania Peñuela

The magnetic flux cancellation on the Sun plays a crucial role in determining the manner in which the net magnetic flux changes in every solar cycle, affecting the large scale evolution of the coronal magnetic fields and heliospheric…

Solar and Stellar Astrophysics · Physics 2020-07-01 Susanta Kumar Bisoi , P. Janardhan

It is well accepted that the solar cycle originates from a magnetohydrodynamics dynamo deep inside the Sun. Many dynamo models have long been proposed based on a lot of observational constraints. In this paper, using 342 NSO/Kitt Peak solar…

Astrophysics · Physics 2009-06-23 W. B. Song

The Sun's global meridional circulation is evident as a slow poleward flow at its surface. This flow is observed to carry magnetic elements poleward - producing the Sun's polar magnetic fields as a key part of the 11-year sunspot cycle.…

Solar and Stellar Astrophysics · Physics 2011-03-30 David H. Hathaway

The change of sound speed has been found at the base of the convection during the solar cycles, which can be used to constrain the solar internal magnetic field. We aim to check whether the magnetic field generated by the solar dynamo can…

Solar and Stellar Astrophysics · Physics 2021-06-02 Shaolan Bi , Tanda Li , Kang Liu , Jie Jiang , Yaguang Li , Jinghua Zhang , Xianfei Zhang , Yaqian Wu

We present independent observations of the solar-cycle variation of flows near the solar surface and at a depth of about 60 Mm, in the latitude range $\pm45^\circ$. We show that the time-varying components of the meridional flow at these…

Astrophysics · Physics 2009-11-13 L. Gizon , M. Rempel

After emerging to the solar surface, the Sun's magnetic field displays a complex and intricate evolution. The evolution of the surface field is important for several reasons. One is that the surface field, and its dynamics, sets the…

Solar and Stellar Astrophysics · Physics 2015-06-22 J. Jiang , D. H. Hathaway , R. H. Cameron , S. K. Solanki , L. Gizon , L. Upton

Solar activity seems quite understandable when considered on the scales comparable with a solar cycle, i.e. about 11 years, and on a short time scale of about a year. A solar cycle looks basically (anti)symmetric with respect to the solar…

Solar and Stellar Astrophysics · Physics 2025-08-08 V. N. Obridko , A. S. Shibalova , D. D. Sokoloff , I. M. Livshits

Human living environment is influenced by intense solar activity. The solar activity exhibits periodicity and regularity. Although many deep-learning models are currently used for solar cycle prediction, most of them are based on a…

Solar and Stellar Astrophysics · Physics 2025-03-04 Cui Zhao , Kun Liu , Shangbin Yang , Jinchao Xia , Jingxia Chen , Jie Ren , Shiyuan Liu , Fangyuan He

The key elements of the Babcock-Leighton dynamos are the generation of poloidal field through decay and dispersal of tilted bipolar active regions and the generation of toroidal field through the observed differential rotation. These models…

Solar and Stellar Astrophysics · Physics 2016-11-29 Bidya Binay Karak , Robert Cameron