Time-distance Measurements of Meridional Circulation Deep in the Convection Zone
Abstract
Explaining the solar cycle is one of the central goals of solar physics. Some of the most successful models of the cycle fall under the broad category of Babcock-Leighton dynamo theories. Babcock and Leighton developed this model in the 1960s, making use of the most recent observations of the Sun's magnetic field and surface motions. The model reproduces the large-scale properties of the cycle by invoking both differential rotation and supergranular diffusion of magnetic elements. Although the original work predates the birth of helioseismology, it still underlies much of our current understanding of the solar cycle. The development of helioseismology has, however, necessitated some evolution of the theory. For example, dynamo theorists now must match their models to the observed differential rotation profile in the solar interior. Prodded by more sophisticated surface measurements, several groups have also proposed models including a meridional circulation. Until recently, theorists were free to speculate on the characteristics of this flow below the surface. In the past few years, however, several helioseismic techniques have been used to successfully measure the meridional circulation in the solar interior. In this paper, the authors present their latest measurements of the meridional flow using the time-distance technique on MDI data. These measurements now reach far enough into the convection zone that they might be a useful constraint on solar dynamo theories. This research is supported by NASA contract NAG5-3077 at Stanford University.
- Publication:
-
SOHO-9 Workshop on Helioseismic Diagnostics of Solar Convection and Activity
- Pub Date:
- 1999
- Bibcode:
- 1999soho....9E..23G