Solar Interior Zonal and Meridional Flows Obtained from Time-Distance Helioseismology Analysis

Zhao Junwei, junwei@sun.stanford.edu, Stanford University, United States
Bogart Rick, Stanford University
Kosovichev Alexander, Stanford university
Duvall Tom, NASA Goddard Flight Center

Abstract
A precise determination of rotation rate and meridional flow speed in the solar interior is very important to help understand the physical processes of magnetic field generation and transportation. It was also suggested that the meridional flow speed change is one possible reason that has caused the unusually long activity minimum of Cycle 23. By analyzing SOHO/MDI and SDO/HMI Doppler observations, a combination of which covers over 16 years of the Sun, we infer solar interior zonal and meridional flows up to 100 Mm in depth by utilizing the time-distance helioseismology technique. We also study the connections between changes of the zonal and meridional flow speed and the evolution of the solar cycle.