On photospheric flows and chromospheric corks

Abstract

Proper motions of granules are measured by local correlation tracking on a 4.5 h image sequence obtained with the Swedish Vacuum Tower Telescope at La Palma. A 2arcsec spati l low- pass filter is applied to obtain meso-scale flow patterns.We find that their characteristic lifetime (1 /e value)has a lower limit of five to six hours.Comparison with a simultaneous co-spatial sequence of chromospheric K 2V images shows that these flows sweep supergranulation cells clean in about the s me period. A chromospheric "persistent flasher", seen during three hours in K 2V , migrates to the magnetic network as if it were photospheric cork.