Abstract

Sunspots are surface manifestations of a large-scale magnetic field that rises to the solar photosphere, under the action of magnetic buoyancy, from deep within the solar interior. It is generally accepted that most of the large-scale magnetic flux that appears at the surface originates from the tachocline, which is a region of strong differential rotation around the base of the solar convection zone. Adopting an idealised model that mimics a local region of the tachocline, I will discuss magnetic buoyancy instabilities in a shear-generated magnetic layer. Recent results suggest that such an instability can only operate in rather restricted regions of parameter space, which would have serious implications for the solar tachocline; I will focus particularly upon the extent to which these results actually constrain the magnetic buoyancy instability in this system. Finally, I will describe some preliminary calculations that suggest that shear-driven magnetic buoyancy may be playing a crucial role in the large-scale solar dynamo (for which there is still no universally accepted model