Long-term variations of turbulent transport coefficients in a solar-like convective dynamo simulation

Research output: Contribution to journalArticleScientificpeer-review

Researchers

Research units

  • Max Planck Institutue for Solarsystem Research, Göttingen

Abstract

The Sun, aside from its eleven year sunspot cycle is additionally subject to long term variation in its activity. In this work we analyse a solar-like 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 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 modelling is required for verification.

Details

Original languageEnglish
Pages (from-to)885-895
Number of pages11
JournalAstronomische Nachrichten
Volume338
Issue number8
Publication statusPublished - Oct 2017
MoE publication typeA1 Journal article-refereed

    Research areas

  • convection, magnetohydrodynamics, methods: numerical, stars: magnetic fields, turbulence

ID: 9775167