[P-EM14] Frontiers in solar physics

[PEM14-03] Discussion of Solar Grand Minimum using Surface Flux Transport Model

*梶山 侑里名¹、今田 晋亮¹、飯島 陽久² (1.東京大学大学院理学系研究科地球惑星科学専攻、2.名古屋大学宇宙地球環境研究所)

キーワード：黒点、太陽活動、シミュレーション

Solar activity typically rises and falls in 11-year cycles, as seen in the number of sunspots. It is known that there is a period of extremely low solar activity (grand minimum) once every several hundred years. It has been suggested that such periods of low solar activity may have triggered the Little Ice Age in the past, and it is important to understand the factors that caused such extreme periods of low activity, but these factors are still unknown. Solar activity is strongly correlated with the polar magnetic field of the previous cycle, and it is thought that the polar magnetic field fluctuates as sunspots are transported by advection and diffusion. Sunspots are produced by the solar dynamo and are characterized by parameters such as number, latitude, area and tilt angle. On the other hand, these are statistically indeterminate, and it is not well understood what kind of sunspots contribute to the fluctuations of the polar magnetic field. In this study, we use the surface flux transport model (SFT model) to calculate the polar magnetic field and predict the fluctuation of the polar magnetic field stochastically. As a result, we consider the occurrence probability of the grand minimum and the factors that cause the grand minimum. Our results show that solar activity as low as the Dalton minimum appears once every few hundred years, and that sunspot tilt angles at low latitude cause such minima.