2017/09/30 by Frederick A. Gent, M. J. Käpylä, Maarit J. Käpylä +2 · 9 citations
Biochemistry, Genetics and Molecular Biology · Physics and Astronomy · #Computational physics #Convection #Convection zone #Dipole #Dipole model of the Earth's magnetic field #Dynamo #Dynamo theory #Geomagnetism and Paleomagnetism Studies #Interplanetary magnetic field #Ionosphere and magnetosphere dynamics #Magnetic energy #Magnetic field #Mechanics #Physics #Solar and Space Plasma Dynamics #Solar wind #Statistical physics #Turbulence #astro-ph.SR
paper · pdf · doi:10.1002/asna.201713406
published in Astronomische Nachrichten 338(8), 885-895 (Wiley) · 11 pages, 12 figures, accepted by AN for 14th Potsdam Thinkshop
openalex publication_date 2017/10/01 · arxiv created 2017/10/06 · arxiv updated 2017/10/11 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The Sun, aside from its 11‐year sunspot cycle, is additionally subject to long‐term variation in its activity. In this work, we analyze a solarlike convective dynamo simulation, containing approximately 60 magnetic cycles, exhibiting equatorward propagation of the magnetic field, multiple frequencies, and irregular variability, including a missed cycle and complex parity transitions between dipolar and quadrupolar modes. We compute the turbulent transport coefficients, describing the effects of the turbulent velocity field on the mean magnetic field, using the test‐field method. The test‐field analysis provides a plausible explanation of the missing cycle in terms of the reduction of α ϕϕ in advance of the reduced surface activity and enhanced downward turbulent pumping during the event to confine some of the magnetic field at the bottom of the convection zone, where the local maximum of magnetic energy is observed during the event. At the same time, however, a quenching of the turbulent magnetic diffusivities is observed, albeit differently distributed in depth compared to the other transport coefficients. Therefore, dedicated mean‐field modeling is required for verification.