  We investigate how magnetically driven outflows are powered by a rotating,
weakly magnetized accretion flow onto a supermassive black hole using
axisymmetric magnetohydrodynamic simulations. Our proposed model focuses on the
accretion dynamics on an intermediate scale between the Schwarzschild radius
and the galactic scale, which is $\sim$1-100 pc. We demonstrate that a rotating
disk formed on a parsec-scale acquires poloidal magnetic fields via accretion
and this produces an asymmetric bipolar outflow at some point. The formation of
the outflow was found to follow the growth of strongly magnetized regions
around disk surfaces (magnetic bubbles). The bipolar outflow grew continuously
inside the expanding bubbles. We theoretically derived the growth condition of
magnetic bubbles for our model that corresponds to a necessary condition for
outflow growth. We found that the north-south asymmetric structure of the
bipolar outflow originates from the complex motions excited by accreting flows
around the outer edge of the disk. The bipolar outflow comprises multiple
mini-outflows and downflows (failed outflows). The mini-outflows emanate from
the magnetic concentrations (magnetic patches). The magnetic patches exhibit
inward drifting motions, thereby making the outflows unsteady. We demonstrate
that the inward drift can be modeled using a simple magnetic patch model that
considers magnetic angular momentum extraction. This study could be helpful for
understanding how asymmetric and non-steady outflows with complex substructures
are produced around supermassive black holes without the help of strong
radiation from accretion disks or entrainment by radio jets such as molecular
outflows in radio-quiet active galactic nuclei, NGC 1377.
