Alladi Ramakrishnan Hall

Solar Magnetic Fields and Cycles

Bidya Binay Karak

High Altitude Observatory, Boulder, USA

Solar Magnetic Fields and Cycles: Understanding the Dynamo Mechanism*
The number of sunspots observed on the surface of the Sun varies cyclically
with a period of about 11 years. This is popularly known as the solar
cycle. Sunspots are the manifestations of strong large-scale magnetic
fields of the Sun. These fields are produced by the magnetohydrodynamics
dynamo mechanisms in the convection zone. Due to highly nonlinear nature of
the dynamo processes and the extreme parameters of the solar convection
zone, the origin of the solar magnetic cycle is still not completely
understood. I shall first demonstrate our recent effort in understanding
this magnetic cycle using 3D global convection simulations in spherical
geometry. Then I shall describe a Babcock-Leighton dynamo model in which
bipolar sunspots are deposited into this model based on solar observations.
I shall illustrate that this model is able to explain some basic features
of the solar cycle.