title: Large-scale magnetic fields at high Reynolds numbers in magnetohydrodynamic simulations.
abstract: The 11-year solar magnetic cycle shows a high degree of coherence in spite of the turbulent nature of the solar convection zone. It has been found in recent high-resolution magnetohydrodynamics simulations that the maintenance of a large-scale coherent magnetic field is difficult with small viscosity and magnetic diffusivity (≲10 (12) square centimenters per second). We reproduced previous findings that indicate a reduction of the energy in the large-scale magnetic field for lower diffusivities and demonstrate the recovery of the global-scale magnetic field using unprecedentedly high resolution. We found an efficient small-scale dynamo that suppresses small-scale flows, which mimics the properties of large diffusivity. As a result, the global-scale magnetic field is maintained even in the regime of small diffusivities-that is, large Reynolds numbers.
authors.affiliation: Department of Physics, Graduate School of Science, Chiba University, 1-33 Yayoi-cho, Inage-ku, Chiba 263-8522, Japan. High Altitude Observatory, National Center for Atmospheric Research (NCAR), Post Office Box 3000, Boulder, CO 80307, USA. hotta@chiba-u.jp.
authors.forename: H
authors.initials: H
authors.lastname: Hotta
authors.affiliation: High Altitude Observatory, National Center for Atmospheric Research (NCAR), Post Office Box 3000, Boulder, CO 80307, USA.
authors.forename: M
authors.initials: M
authors.lastname: Rempel
authors.affiliation: Department of Earth and Planetary Science, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-0033, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Yokoyama