Title: Meridional Circulation Dynamics in a Cyclic Convective Dynamo,
Abstract: Surface observations indicate that the speed of the solar meridional
circulation in the photosphere varies in anti-phase with the solar cycle. The
current explanation for the source of this variation is that inflows into
active regions alter the global surface pattern of the meridional circulation.
When these localized inflows are integrated over a full hemisphere, they
contribute to the slow down of the axisymmetric poleward horizontal component.
The behavior of this large scale flow deep inside the convection zone remains
largely unknown. Present helioseismic techniques are not sensitive enough to
capture the dynamics of this weak large scale flow. Moreover, the large time of
integration needed to map the meridional circulation inside the convection
zone, also masks some of the possible dynamics on shorter timescales. In this
work we examine the dynamics of the meridional circulation that emerges from a
3D MHD global simulation of the solar convection zone. Our aim is to assess and
quantify the behavior of meridional circulation deep inside the convection
zone, where the cyclic large-scale magnetic field can reach considerable
strength. Our analyses indicate that the meridional circulation morphology and
amplitude are both highly influenced by the magnetic field, via the impact of
magnetic torques on the global angular momentum distribution. A dynamic feature
induced by these magnetic torques is the development of a prominent upward flow
at mid latitudes in the lower convection zone that occurs near the equatorward
edge of the toroidal bands and that peaks during cycle maximum. Globally, the
dynamo-generated large-scale magnetic field drives variations in the meridional
flow, in stark contrast to the conventional kinematic flux transport view of
the magnetic field being advected passively by the flow.