Shedding light on the sun through the calibration of solar dynamo models on millennial records of solar activity
Simone Ulzega
Shedding light on the sun through the calibration of solar dynamo models on millennial records of solar activity
Simone Ulzega
Abstract
A lot of effort has gone into the development of sound physics-based stochastic solar dynamo models capable of explaining a wide variety of characteristic phenomena such as periodic cycles and occurrences of Grand Minima. However, model parameters need to be first calibrated to measured data in a consistent framework such as the Bayesian one. Unfortunately, Bayesian parameter calibration with stochastic models is a computationally very challenging task, requiring sophisticated algorithms and appropriate hardware. Moreover, a reliable parameter calibration for solar dynamo models has been hindered so far by the lack of data over a time span comparable to solar dynamics time scales, as the only available direct observations of long-term solar magnetic activity are sunspot number records, covering only about 300 years. However, time-series of cosmogenic radionuclides (Brehm et al. 2021, Usoskin et al. 2021) are proxies for solar magnetic activity on a millennial time scale, which can potentially shed light on several open questions, e.g., occurrences of Grand Minima and long-period cycles, and boost our understanding and predictive capabilities of the solar dynamo. We present here our first attempts to apply advanced Bayesian inference methods to the calibration of a stochastic delay differential equation solar dynamo model, and discuss hardships, perspectives and dreams.