  We investigate surface processes of magnetic patches, namely merging,
splitting, emergence, and cancellation, by using an auto-detection technique.
We find that merging and splitting are locally predominant in the surface
level, while the frequencies of the other two are less by one or two orders of
magnitude. The frequency dependences on flux con- tent of surface processes are
further investigated. Based on these observations, we discuss a possible whole
picture of the maintenance. Our conclusion is that the photospheric magnetic
field structure, especially its power-law nature, is maintained by the
processes locally in the surface not by the interactions between different
altitudes. We suggest a scenario of the flux maintenance as follows: The
splitting and merging play a crucial role for the generation of the power-law
distribution, not the emergence nor cancellation do. This power-law
distribution results in another power-law one of the cancellation with an idea
of the random convective transport. The cancellation and emergence have a
common value for the power-law indices in their frequency distributions, which
may suggest a "recycle of fluxes by submergence and re-emergence".
