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DTSTAMP:20260625T133338Z
LOCATION:Bldg. 6 - 001 - Plenary Room
DTSTART;TZID=Europe/Stockholm:20260630T122100
DTEND;TZID=Europe/Stockholm:20260630T122300
UID:submissions.pasc-conference.org_PASC26_sess129_pos115@linklings.com
SUMMARY:P35 - Shedding Light on the Solar Dynamo Using Bayesian Data Scien
 ce
DESCRIPTION:Simone Ulzega (Zurich University of Applied Sciences, Institut
 e of Computational Life Sciences) and Carlo Albert (Swiss Federal Institut
 e of Aquatic Science and Technology (EAWAG))\n\nSolar magnetic activity ex
 hibits an approximately 11-year cycle that is far from stable, showing str
 ong long-term variability and recurrent episodes of strongly reduced activ
 ity known as Grand Minima. Understanding the origin of these features rema
 ins a fundamental challenge in solar physics and is crucial for improving 
 predictions of solar activity. We investigate the hypothesis that the sola
 r dynamo operates near a critical bifurcation point at which two oscillato
 ry regimes coexist, corresponding to normal and Grand-Minimum-like activit
 y. We employ a zero-dimensional stochastic dynamo model formulated as a st
 ochastic delay differential equation, which exhibits bistability and noise
 -induced transitions between weak and strong dynamo modes. Model parameter
 s are inferred using simulation-based Bayesian methods that rely on forwar
 d simulations. We apply two independent approaches: a Simulated Annealing 
 Approximate Bayesian Computation algorithm and a neural simulation-based i
 nference method based on normalizing flows. Using both the observed sunspo
 t record and a millennial-scale reconstruction, we obtain consistent poste
 rior distributions concentrated near the critical bifurcation point, suppo
 rting a near-critical interpretation of the solar dynamo.\n\nSession Chair
 : Tobias Hodel (University of Bern, Switzerland)\n\n
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