Task A4: Flux tube emergence in turbulent convection zones (PhD1 & 2, Yrs 1,2,3,4) Scientists involved: A.S. Brun, R. Pinto, L. Jouve We wish to study magnetic buoyancy (see text above and fig 1). These 3-D MHD simulations with the ASH code, seek to study the emergence from the base of the convection zone with differential rotation and meridional circulation of 3-D toroidal structures toward the surface (Jouve & Brun 2007), with here a specific attention to the treatment of the surface. As of today the ASH code uses an impenetrable top boundary (Vr(r=rtop)=0). We here propose to include a stable zone above the convective envelope in order to allow the flux tube to emerge in an unconstrained environment, without imposing boundary conditions (even potential) since the MHD equations will be solved beyond the convection edge. This will also allow to have a more irregular (rough) convection surface and to allow for large density variations and or a change of plasma beta. These cases will be compared to simpler cases assuming impenetrable BC's. Comparison will be made with task A3 in which toroidal structures will be self consistently generated by the models and not introduced by hand. Key questions: How does magnetic flux ropes rise through turbulent, rotating convection zone? Is Joy's law characterizing the tilt of active regions a direct consequence of the tilt of toroidal structures during their rise? How differential rotation, meridional flows, background convection, dynamo generated fields and the plasma beta influence flux emergence? THREE-DIMENSIONAL NONLINEAR EVOLUTION OF A MAGNETIC FLUX TUBE IN A SPHERICAL SHELL: INFLUENCE OF TURBULENT CONVECTION AND ASSOCIATED MEAN FLOWS L. Jouve and A. S. Brun ,The Astrophysical Journal, 701:1300 1322, 2009 August 20 3D MHD Modelling of a chromosphere above the sun's convective zone R. Pinto and A. S. Brun Magnetic Wreaths and Cycles in Convective Dynamos. Nelson, N.J., Brown, B.P., Brun, A.S., Miesch, M.S., Toomre, J. 2013. ,The Astrophysical Journal 762, 73. Global dynamics of subsurface solar active regions. Jouve, L., Brun, A.S., Aulanier, G. 2013. ,The Astrophysical Journal 762, 4. Buoyant Magnetic Loops in a Global Dynamo Simulation of a Young Sun. Nelson, N.J., Brown, B.P., Brun, A.S., Miesch, M.S., Toomre, J. 2011. ,The Astrophysical Journal 739, L38. Buoyant Magnetic Loops Generated by Global Convective Dynamo Action N. J. Nelson, B. P. Brown, A. S. Brun, M. S. Miesch, J. Toomre, Solar Phys DOI 10.1007/s11207-012-0221-4