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Physics-based solar cycle predictions provide an effective way to verify our understanding of the solar cycle. Before the start of cycle 25, several physics-based solar cycle predictions were developed. These predictions use flux transport…

Solar and Stellar Astrophysics · Physics 2023-02-08 Jie Jiang , Zebin Zhang , Kristóf Petrovay

Converging flows are visible around bipolar magnetic regions (BMRs) on the solar surface, according to observations. Average flows are created by these inflows combined, and the strength of these flows depends on the amount of flux present…

Solar and Stellar Astrophysics · Physics 2025-04-07 Mohammed H. Talafha , Kristóf Petrovay , Andrea Opitz

With multiple vantage points around the Sun, STEREO and SDO imaging observations provide a unique opportunity to view the solar surface continuously. We use He II 304 A data from these observatories to isolate and track ten active regions…

Solar and Stellar Astrophysics · Physics 2015-12-16 Ignacio Ugarte-Urra , Lisa Upton , Harry P. Warren , David H. Hathaway

The solar surface magnetic field is fundamental for modeling the coronal magnetic field, studying the solar dynamo, and predicting solar cycle strength. We perform a continuous simulation of the surface magnetic field from 2010 to 2024,…

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

Most of the intracyclic variability in the large-scale solar magnetic field comes from the equatorial dipole component of the solar magnetic field. The equatorial dipole component is highly sensitive to the longitude distribution of the…

Solar and Stellar Astrophysics · Physics 2026-03-09 Ismo Tähtinen , Timo Asikainen , Kalevi Mursula

Reliable prediction of the solar cycle is a formidable challenge, yet it is increasingly vital in our technology-dependent society as solar activity drives space weather. Various methods, including precursors, nonlinear curve fitting and…

Solar and Stellar Astrophysics · Physics 2026-04-20 Bidya Binay Karak

Context. Solar dipole captures important information about the large-scale solar magnetic field. The evolution of the solar magnetic field including the solar dipole can be simulated with a surface flux transport (SFT) model, but these…

Solar and Stellar Astrophysics · Physics 2026-04-29 Ismo Tähtinen , Timo Asikainen , Kalevi Mursula

As a large-scale motion on the Sun, the meridional flow plays an important role in determining magnetic structure and strength and solar cycle. However, the meridional flow near the solar poles is still unclear. The Hinode observations show…

Solar and Stellar Astrophysics · Physics 2024-07-29 Shuhong Yang , Jie Jiang , Zifan Wang , Yijun Hou , Chunlan Jin , Qiao Song , Yukun Luo , Ting Li , Jun Zhang , Yuzong Zhang , Guiping Zhou , Yuanyong Deng , Jingxiu Wang

The tilt angles of sunspot groups represent the poloidal field source in Babcock-Leighton-type models of the solar dynamo and are crucial for the build-up and reversals of the polar fields in Surface Flux Transport (SFT) simulations. The…

Solar and Stellar Astrophysics · Physics 2015-06-22 J. Jiang , R. H. Cameron , M. Schuessler

One possible scenario for the origin of the solar tachocline, known as the "fast tachocline", assumes that the turbulent diffusivity exceeds eta>10^9 cm^2/s. In this case the dynamics will be governed by the dynamo-generated oscillatory…

Astrophysics · Physics 2009-11-07 E. Forgacs-Dajka , K. Petrovay

Knowledge of the global magnetic field distribution and its evolution on the Sun's surface is crucial for modeling the coronal magnetic field, understanding solar wind dynamics, computing the heliospheric open flux distribution and…

Solar and Stellar Astrophysics · Physics 2024-09-24 Soumyaranjan Dash , Marc L. DeRosa , Mausumi Dikpati , Xudong Sun , Sushant S. Mahajan , Yang Liu , J. Todd Hoeksema

Decay and dispersal of the tilted Bipolar Magnetic Regions (BMRs) on the solar surface are observed to produce large-scale poloidal field, which acts as the seed for the toroidal field and, thus, the next sunspot cycle. However, various…

Solar and Stellar Astrophysics · Physics 2024-04-17 Pawan Kumar , Bidya Binay Karak , Anu Sreedevi

Detailed study of the solar magnetic field is crucial to understand its generation, transport and reversals. The timing of the reversals may have implications on space weather and thus identification of the temporal behavior of the critical…

The magnetic fields in the solar polar region are important to our understanding of the internal dynamo process, the global coronal structure, and the origin of the solar wind. The inference of polar fields based on spectropolarimetric…

Solar and Stellar Astrophysics · Physics 2026-03-16 Bryan Yamashiro , Xudong Sun , Ivan Milić , Carlos Quintero Noda , Adur Pastor Yabar , Rebecca Centeno , Jiayi Liu , Milan Gošić , Kai Yang

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

Using time-distance helioseismology applied to 14-years of SDO/HMI observations spanning solar cycle 24 and rising phase of cycle 25, we present evidence that meridional flows in the lower half of the near-surface shear layer (NSSL),…

Solar and Stellar Astrophysics · Physics 2026-04-21 Anisha Sen , S. P. Rajaguru , Ruizhu Chen , Junwei Zhao , Shukur Kholikov

Space weather is a matter of practical importance in our modern society. Predictions of forecoming solar cycles mean amplitude and duration are currently being made based on flux-transport numerical models of the solar dynamo. Interested in…

Solar and Stellar Astrophysics · Physics 2013-12-05 Sabrina Maite Sanchez , Alexandre Fournier , Julien Aubert

Polar fields in solar cycle 23 were about 50% weaker than those in cycle 22. The only theoretical models which have addressed this puzzle are surface transport models and flux-transport dynamo models. Comparing polar fields obtained from…

Solar and Stellar Astrophysics · Physics 2015-05-27 Mausumi Dikpati

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 solar cycle and its associated magnetic activity are the main drivers behind changes in the interplanetary environment and the Earth's upper atmosphere (commonly referred to as space weather). These changes have a direct impact on the…

Solar and Stellar Astrophysics · Physics 2013-04-12 Andrés Muñoz-Jaramillo , María Dasi-Espuig , Laura A. Balmaceda , Edward E. DeLuca