Top: three-dimensional images of a disconnected active region in KD3 with depth 0.65 R_⊙ (left) and 0.95 R_⊙ (right). The radial magnetic field is shown at the transparent surface and field lines below the surface. Bottom: unsigned surface flux from 3D simulations of a single disconnected active region with depth 0.65 R_⊙ (dashed), 0.8 R_⊙ (dash-dotted) and 0.95 R_⊙ (solid), using the quenching profile. The equivalent 2D SFT flux is shown in the dotted blue (without decay) and black (with decay) curves.