  We present a new methodology which can determine magnetic helicity transport
by the passage of helical magnetic field lines from sub-photosphere and the
shuffling motions of foot-points of preexisting coronal field lines separately.
It is well known that only the velocity component which is perpendicular to the
magnetic field ($\upsilon_{\perp B}$) has contribution to the helicity
accumulation. Here, we demonstrate that $\upsilon_{\perp B}$ can be deduced
from horizontal motion and vector magnetograms, under a simple relation of
$\upsilon_t = \mu_t + \frac{\upsilon_n}{B_n} B_t$ as suggested by
D$\acute{e}$moulin & Berger (2003). Then after dividing $\upsilon_{\perp B}$
into two components, as one is tangential and the other is normal to the solar
surface, we can determine both terms of helicity transport. Active region (AR)
NOAA 10930 is analyzed as an example during its solar disk center passage by
using data obtained by the Spectro-Polarimeter and the Narrowband Filter Imager
of Solar Optical Telescope on board Hinode. We find that in our calculation,
the helicity injection by flux emergence and shuffling motions have the same
sign. During the period we studied, the main contribution of helicity
accumulation comes from the flux emergence effect, while the dynamic transient
evolution comes from the shuffling motions effect. Our observational results
further indicate that for this AR, the apparent rotational motion in the
following sunspot is the real shuffling motions on solar surface.

Solar and Stellar Astrophysics