HAO along with researchers from the Max Planck Institute for Solar System Research, The University of Göttingen, and NorthWest Research Associates have now shown that magnetic flux concentrations forming active regions on the sun emerge at a rate much slower than predicted by the prevailing current model.
For their study, which was published July 13 in the journal Science Advances, they compared satellite observations from the NASA Solar Dynamics Observatory (SDO) and computer simulations performed by HAO scientist Matthias Rempel. It was found that typical emergence velocities cannot exceed 150 m/s in a depth of 20,000 km beneath the solar photosphere, which is a velocity comparable to convective motions. This shows that convection in the solar interior plays a crucial role even for active region scale flux emergence.
http://www.mps.mpg.de/slow-appearance-of-sunspots-challenges-theory