Effects of a subadiabatic layer on convection and dynamos in spherical wedge simulations. Issue 1 (4th March 2019)

• Record Type: Journal Article
• Authors: Käpylä, P. J.; Viviani, M.; Käpylä, M. J.; Brandenburg, A.; Spada, F.
• Is Part Of: Geophysical and astrophysical fluid dynamics. Volume 113:Issue 1/2(2019)
• Page Start: 149
• Page End: 183
• Publication Date: 2019-03-04
• Subjects: Convection -- turbulence -- dynamos -- magnetohydrodynamics; Fluid dynamics -- Periodicals; Astrophysics -- Periodicals; Geophysics -- Periodicals; 551
• DOI: 10.1080/03091929.2019.1571584
• Languages: English
• ISSNs: 0309-1929

Abstract

ABSTRACT: We consider the effect of a subadiabatic layer at the base of the convection zone on convection itself and the associated large-scale dynamos in spherical wedge geometry. We use a heat conduction prescription based on the Kramers opacity law which allows the depth of the convection zone to dynamically adapt to changes in the physical characteristics such as rotation rate and magnetic fields. We find that the convective heat transport is strongly concentrated towards the equatorial and polar regions in the cases without a substantial radiative layer below the convection zone. The presence of a stable layer below the convection zone significantly reduces the anisotropy of radial enthalpy transport. Furthermore, the dynamo solutions are sensitive to subtle changes in the convection zone structure. We find that the kinetic helicity changes sign in the deeper parts of the convection zone at high latitudes in all runs. This region expands progressively towards the equator in runs with a thicker stably stratified layer.