Simulating solar MHD

Two aspects of solar MHD are discussed in relation to the work of the MHD s imulation group at KIS, Photospheric magneto-convection, the nonlinear inte raction of magnetic field and convection in a strongly stratified, radiatin g fluid, is a key process of general astrophysical relevance. Comprehensive numerical simulations including radiative transfer have significantly impr oved our understanding of the processes and have become an important tool f or the interpretation of observational data. Examples of field intensificat ion in the solar photosphere ('convective collapse') are shown. The second line of research is concerned with the dynamics of Aux tubes in the convect ion zone, which has far-reaching implications for our understanding of the solar dynamo. Simulations indicate that the field strength in the region wh ere the flux is stored before erupting to form sunspot groups is of the ord er of 10(5) G, an order of magnitude larger than previous estimates based o n equipartition with the kinetic energy of convective flows.