CYCLIC MAGNETIC ACTIVITY DUE TO TURBULENT CONVECTION IN SPHERICAL WEDGE GEOMETRY

By Petri J. Käpylä, M. Mantere, Axel Brandenburg. 2012

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We report on simulations of turbulent, rotating, stratified, magnetohydrodynamic convection in spherical wedge geometry. An initially small-scale, random, weak-amplitude magnetic field is amplified by several orders of magnitude in the course of the simulation to form oscillatory large-scale fields in the saturated state of the dynamo. The differential rotation is solar-like (fast equator), but neither coherent meridional poleward circulation nor near-surface shear layer develop in these runs. In addition to a poleward branch of magnetic activity beyond 50° latitude, we find for the first time a pronounced equatorward branch at around 20° latitude, reminiscent of the solar cycle.

Subfields: Astronomy and Astrophysics, Computational Mechanics, Molecular Biology

View Paper: https://www.semanticscholar.org/paper/a6430fc8c040b22f5c791f404118d2b0c1a5faab

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Citations in the corpus

The Maunder minimum (1645–1715) was indeed a grand minimum: A reassessment of multiple datasets (2015, methodology): “…part of the behaviour of the large-scale solar magnetic ﬁeld (Ghizaru et al. 2010; Brown et al. 2011; Schrinner et al. 2012; Gastine et al. 2012; Käpylä et al. 2012), it is still challenging to extend the integration time over several magnetic cycles as needed to reproduce a Maunder-like…”
DETECTION OF EQUATORWARD MERIDIONAL FLOW AND EVIDENCE OF DOUBLE-CELL MERIDIONAL CIRCULATION INSIDE THE SUN (2013, background): “However, on the other hand, solar convection simulations have shown the possibility of multi-cell circulation with a shallow equatorward flow (e.g., Miesch et al. 2006; Käpylä et al. 2012; Guerrero et al. 2013), demonstrating that our analysis results are reasonable.”
Solar Dynamo Theory (2014, methodology): “…poleward propagation of the low-latitude toroidal field in the kinematic growth phase of the large-scale dynamo switches to equatorward propagation following nonlinear saturation (see Käpylä et al. 2012, their figure 3; see also Figure 4 herein), consistent with a sign change in the α-effect.”
MAGNETIC WREATHS AND CYCLES IN CONVECTIVE DYNAMOS (2012, background): “It is also closely related to the negative magnetic pressure instability described by Kleeorin et al. (1989) (see also Rogachevskii & Kleeorin 2007; Käpylä et al. 2012; Kemel et al. 2012), although it does not necessarily rely on the assumptions that underlie that instability analysis, namely…”