  We investigated the role of photospheric plasma motions in the formation and
evolution of polar magnetic patches using time-sequence observations with high
spatial resolution. The observations were obtained with the spectropolarimeter
on board the Hinode satellite. From the statistical analysis using 75 magnetic
patches, we found that they are surrounded by strong converging,
supergranulation associated flows during their apparent life time and that the
converging flow around the patch boundary is better observed in the Doppler
velocity profile in the deeper photosphere. Based on our analysis we suggest
that the like-polarity magnetic fragments in the polar region are advected and
clustered by photospheric converging flows thereby resulting in the formation
of polar magnetic patches. Our observations show that, in addition to direct
cancellation magnetic patches decay by fragmentation followed by unipolar
disappearance or unipolar disappearance without fragmentation. It is possible
that the magnetic patches of existing polarity fragment or diffuse away into
smaller elements and eventually cancel out with opposite polarity fragments
that reach the polar region around solar cycle maximum. This could be one of
the possible mechanisms by which the existing polarity decay during the
reversal of the polar magnetic field.
