Letter to the Editor

The penetration of meridional flow into the tachocline and its meaning for the solar dynamo

¹ Astrophysikalisches Institut Potsdam, An der Sternwarte 16, 14482 Potsdam, Germany e-mail: [gruediger;rarlt]@aip.de
² Institute for Solar-Terrestrial Physics, PO Box 4026, Irkutsk 664033, Russian Federation e-mail: kit@iszf.irk.ru

Received: 26 August 2005
Accepted: 26 October 2005

Abstract

The penetration of meridional flow into the radiative solar interior is computed with a mean-field model for global circulation in convective zones. The results clearly show that the penetration under solar conditions belongs to the Ekman regime. The penetration is too weak to play any role in the solar dynamo mechanism. We argue, however, that this penetration is sufficient to configure the internal magnetic field of the radiative core so that the solar tachocline can be explained as a Hartmann layer. The resulting meridional flow at the base of the convection zone is fast enough (~7 m/s) to realize an advection-dominated -dynamo within the convection zone.