Alexander Kosovichev/Stanford
University
Determination
of the Large-Scale
and Meridional Flows in the Deep Convection Zone by Time-Distance
Helioseismology
We propose a focused investigation with
the main goal of detecting the return meridional flow and measuring the
properties of deep large-scale flows associated with formation of
active regions. Determination of the large-scale and meridional flows
in the solar convection zone is crucial for understanding and modeling
the solar dynamo and making sort- and long-term predictions of solar
activity. There is no doubt that the large-scale and meridional flows
play a significant role in the dynamo operation and in the generation
of active regions.
The local helioseismology inferences have revealed a complicated
dynamics associated with the meridional flux transport and evolution of
active regions in the upper convection zone. It has been shown that
these inferences have a profound effect on the flux-transport
mechanism. However, the effects of these flows on the properties of the
solar dynamo and active region formation are far from understanding.
For this it is particularly important to determine the structure and
dynamics of these flows in the deep convection zone including the
tachocline where the solar magnetic fields are believed to be generated
and organized.
This problem is difficult because the deep flows are relatively weak,
and their helioseismic signals are difficult to extract from the noisy
oscillation data contaminated by the surface magnetism effects. For
tuning of the helioseismic measurements and verification and testing of
the results we propose to use numerical simulations of stochastically
excited acoustic waves in 3D MHD models of the whole Sun, and use the
simulation data for developing, the helioseismic techniques. This work
includes a thorough investigation of systematic errors and
uncertainties, including potential contamination by the surface
magnetism effect.
