Horizontal Motion of Granules in the Vicinity of Sunspots

Many sunspots in late phases of evolution are surrounded by an annular "moat", where systematic horizontal flows radially away from the sunspot are observed. Applying the local correlation tracking technique to series of white-light images acquired by the satellite TRACE, we use photospheric granules to track horizontal motions in the vicinity of sunspots of different sizes, shapes, and phases of evolution. We define the moat regions on the basis of granular motions. We present preliminary results about the relations between the sunspot types and the occurrence, areas, and velocities of the moats. Further we analyze observed asymmetries in moat shapes and velocities and their relation to the sunspot age and proper motion.