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Near-surface shear layer dynamics

Published online by Cambridge University Press:  01 August 2006

Axel Brandenburg
Axel Brandenburg*
Affiliation:
Nordita, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark and AlbaNova University Center, SE – 106 91 Stockholm, Sweden email: brandenb@nordita.dk
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Abstract

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The outer surface layers of the sun show a clear deceleration at low latitudes. This is generally thought to be the result of a strong dominance of vertical turbulent motions associated with strong downdrafts. This strong negative radial shear should not only contribute to amplifying the toroidal field locally and to expelling magnetic helicity, but it may also be responsible for producing a strong prograde pattern speed in the supergranulation layer. Using simulations of rotating stratified convection in cartesian boxes located at low latitudes around the equator it is shown that in the surface layers patterns move in the prograde direction on top of a retrograde mean background flow. These patterns may also be associated with magnetic tracers and even sunspot proper motions that are known to be prograde relative to the much slower surface plasma.

Keywords

ConvectionhydrodynamicsinstabilitiesMHDturbulencewavesSun: activitygranulationhelioseismologymagnetic fieldsrotation
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S239: Convection in Astrophysics , August 2006 , pp. 457 - 466
Copyright
Copyright © International Astronomical Union 2007

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