Solar active regions as a percolation phenomenon .2.

The persistence of solar active regions was previously modeled in terms of percolation releasing magnetic flux from deep in the solar interior (Wentzel & Seiden 1992). Harvey's (1993) data on the size distribution of active regions at the end of emergence are reinterpreted in terms of a power law at small sizes and exponential at larger sizes. This combination is characteristic of percolation near the critical point. We have added a simple model for the magnetic polarity of the released loops and for their diffusion once they reach the surface. We present simulated active-region maps and size and age distributions.