Meridional Circulation and the Solar Magnetic Cycle

The Sun’s magnetic cycle manifests itself in an year periodic variation in the number of sunspots seen on the solar surface and a periodic reversal in the polarity of its large-scale magnetic fields. Exploring the origins of this magnetic cycle can unravel the physical mechanisms at work in the interior of magnetized stars like the Sun. Such studies are also important for understanding how the Sun’s magnetic output shapes the near-Earth Space environment. Over half a Century of research suggests that a magnetohydrodynamic dynamo mechanism produces the magnetic activity that we see in Sun-like stars. In this review, following a summary of solar observations and the main aspects of the dynamo mechanism, I shall go on to discuss recent theoretical and observational developments, which provide evidence that a meridional flow of material in the interior of the Sun and the interaction of this flow with magnetic fields, is primarily responsible for controlling the period and perhaps also the strength of the solar magnetic cycle.