Temporal evolution of a sunspot in a 16.384 Mm deep domain using an open bottom boundary condition (symmetric in all three mass flux components). The simulation was restarted from the snapshot at t = 8.8 hr shown in Figure 1; the elapsed time is relative to t = 0 hr to be comparable to Figure 1. The open boundary condition leads to a stronger deformation and fragmentation, compared to the reference run shown in Figure 1, but even at t = 46.3 hr the larger fraction of the flux remains concentrated within the main sunspot (see Figure 14). Compared to the 6 Mm deep domain presented in Figure 12, dynamical timescales near the bottom are about 6–8 times longer.

(An animation of this figure is available in the online journal.)