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Synoptic magnetograms provide us with knowledge about the evolution of magnetic fields on the solar surface and present important information for forecasting future solar activity. In this work, poloidal and toroidal magnetic field…

Solar and Stellar Astrophysics · Physics 2020-02-19 Irina N. Kitiashvili

In 1844 Schwabe discovered that the number of sunspots increased and decreased over a period of about 11 years, that variation became known as the sunspot cycle. Almost eighty years later, Hale described the nature of the Sun's magnetic…

We introduce a score-filter-enhanced data assimilation framework designed to reduce predictive uncertainty in machine learning (ML) models for data-driven dynamical system forecasting. Machine learning serves as an efficient numerical model…

Dynamical Systems · Mathematics 2026-03-17 Jingqiao Tang , Ryan Bausback , Feng Bao , Guannan Zhang , Phuoc-Toan Huynh

The mainstream dynamo models predict that the sunspot cycle is non-stationary and stochastic. The official Solar Cycle Prediction Panel forecasts only the ongoing sunspot cycle because any forecast beyond one cycle is considered impossible.…

Solar and Stellar Astrophysics · Physics 2025-08-14 Lauri Jetsu

Filaments are very common physical phenomena on the Sun and are often taken as important proxies of solar magnetic activities. The study of filaments has become a hot topic in the space weather research. For a more comprehensive…

A hybrid data assimilation algorithm is developed for complex dynamical systems with partial observations. The method starts with applying a spectral decomposition to the entire spatiotemporal fields, followed by creating a machine learning…

Computational Physics · Physics 2022-12-27 Changhong Mou , Leslie M. Smith , Nan Chen

The dynamic activity of stars such as the Sun influences (exo)planetary space environments through modulation of stellar radiation, plasma wind, particle and magnetic fluxes. Energetic stellar phenomena such as flares and coronal mass…

Solar and Stellar Astrophysics · Physics 2023-07-26 Prantika Bhowmik , Jie Jiang , Lisa Upton , Alexandre Lemerle , Dibyendu Nandy

A Data Assimilation (DA) strategy based on an ensemble Kalman filter (EnKF) is used to enhance the predictive capabilities of scale resolving numerical tools for the analysis of flows exhibiting cyclic behaviour. More precisely, an ensemble…

Fluid Dynamics · Physics 2025-03-20 Lucas Villanueva , Karine Truffin , Jacques Borée , Marcello Meldi

Artificial intelligence (AI)-based weather prediction research is growing rapidly and has shown to be competitive with the advanced dynamic numerical weather prediction models. However, research combining AI-based weather prediction models…

Machine Learning · Computer Science 2025-10-16 Shunji Kotsuki , Kenta Shiraishi , Atsushi Okazaki

The inherent stochastic and nonlinear nature of the solar dynamo makes the strength of the solar cycles vary in a wide range, making it difficult to predict the strength of an upcoming solar cycle. Recently, our work has shown that by using…

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

A physics-based methodology for the determination of the localization function for the Ensemble Kalman Filter (EnKF) is proposed. The spatial features of such function evolve dynamically over time according to the relevant instantaneous…

Fluid Dynamics · Physics 2025-11-13 Sarp Er , Marcello Meldi

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

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

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 weather and climate domains are undergoing a significant transformation thanks to advances in AI-based foundation models such as FourCastNet, GraphCast, ClimaX and Pangu-Weather. While these models show considerable potential, they are…

Machine Learning · Computer Science 2024-07-18 Junqi Yin , Siming Liang , Siyan Liu , Feng Bao , Hristo G. Chipilski , Dan Lu , Guannan Zhang

This work introduces a new, distributed implementation of the Ensemble Kalman Filter (EnKF) that allows for non-sequential assimilation of large datasets in high-dimensional problems. The traditional EnKF algorithm is computationally…

Machine Learning · Statistics 2023-11-23 Cédric Travelletti , Jörg Franke , David Ginsbourger , Stefan Brönnimann

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

Data assimilation algorithms are used to estimate the states of a dynamical system using partial and noisy observations. The ensemble Kalman filter has become a popular data assimilation scheme due to its simplicity and robustness for a…

Numerical Analysis · Mathematics 2021-06-23 Gottfried Hastermann , Maria Reinhardt , Rupert Klein , Sebastian Reich

A review of solar cycle prediction methods and their performance is given, including early forecasts for cycle 25. The review focuses on those aspects of the solar cycle prediction problem that have a bearing on dynamo theory. The scope of…

Solar and Stellar Astrophysics · Physics 2020-03-05 Kristof Petrovay

There has been a recent surge in development of accurate machine learning (ML) weather prediction models, but evaluation of these models has mainly been focused on medium-range forecasts, not their performance in cycling data assimilation…

Atmospheric and Oceanic Physics · Physics 2024-12-25 Laura C. Slivinski , Jeffrey S. Whitaker , Sergey Frolov , Timothy A. Smith , Niraj Agarwal
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