Measuring the Solar Meridional Circulation Using Local Helioseismology

Abstract:

The solar meridional circulation plays an important role in the transport of angular momentum and magnetic field throughout the convection zone and is a key component in setting the time-scale for the solar cycle in flux-transport dynamo models. The meridional flow is detectable with a variety of methods, including ring-diagram helioseismology. Many of these methods are plagued with systematic errors that have only recently been analyzed in detail. For ring-diagram analysis, the systematic errors introduce a signal that is easily confused with that of the meridional flow and is often of significant amplitude. Accurately determining the character of the solar meridional circulation requires careful attention to these errors. I use observations from the Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) to measure both the meridional flow and the associated systematics. I will present recent measurements of the solar meridional circulation with all known systematics accounted for.