  Recent work by Mitra et al. (2014) has shown that in strongly stratified
forced two-layer turbulence with helicity and corresponding large-scale dynamo
action in the lower layer, a magnetic field occurs in the upper layer in the
form of sharply bounded bipolar magnetic spots. Here we extend this model to
spherical wedge geometry covering the northern hemisphere up to 75{\deg}
latitude and an azimuthal extent of 180{\deg}. The kinetic helicity and
therefore also the large-scale magnetic field are strongest at low latitudes.
For moderately strong stratification, several bipolar spots form that fill
eventually the full longitudinal extent. At early times, the polarity of spots
reflects the orientation of the underlying azimuthal field, as expected from
{\Omega}-shaped flux loops. At late times their tilt changes such that there is
a radial field of opposite orientation at different latitudes separated by
about 10{\deg}. Our model demonstrates the spontaneous formation of spots of
sizes much larger than the pressure scale height. Their tendency to produce
filling factors close to unity is argued to be reminiscent of highly active
stars. We confirm that strong stratification and strong scale separation are
essential ingredients behind magnetic spot formation, which appears to be
associated with downflows at larger depths.
