Effect of noise on sunspot magnetic field parameters

Abstract

AbstractUsing a perturbated (noised) dipole model of a sunspot magnetic field structure we simulated the influence of background noise or apparent noise (unresolved small‐scale magnetic field structure) on sunspot magnetic field parameters.We evaluated mean values of the vertical and horizontal electric current densities |j|∥ and |j|⊥, respectively, of the force‐free parameter α and of the Lorentz force |F|. For comparison we estimated |j⊥| and |F| of a standard sunspot magnetic field model (return‐flux model, OSHEROVICH 1982). Furthermore, we compared our results with those from observations resulting in estimated values of |j|∥ for quiet sunspots. Our investigation led to the following results: the estimated values of 〈|F|〉 show clearly that due to the noise the axisymmetric magnetic dipole model is clustered into several subsystems of fluxbundles. The latter are connected with a system of electric current densities of the order of |j|∥ ∼ 10−3 Am−2 and |j|⊥ = 10−1 Am−2, i.e., this system is a noise‐generated nonaxisymmetric magnetohydrostatic model.