We report results from global ideal MHD simulations that study thin accretion disks ( with thermal scale height H / R =0.1 and 0.05 ) threaded by net vertical magnetic fields .
Our computations span three orders of magnitude in radius , extend all the way to the pole , and are evolved for more than one thousand innermost orbits .
We find that : ( 1 ) inward accretion occurs mostly in the upper magnetically dominated regions of the disk at z \sim R , similar to predictions from some previous analytical work and the ” coronal accretion ” flows found in GRMHD simulations .
( 2 ) A quasi-static global field geometry is established in which flux transport by inflows at the surface is balanced by turbulent diffusion .
The resulting field is strongly pinched inwards at the surface .
A steady-state advection-diffusion model , with turbulent magnetic Prandtl number of order unity , reproduces this geometry well .
( 3 ) Weak unsteady disk winds are launched beyond the disk corona with the Alfvén radius R _ { A } / R _ { 0 } \sim 3 .
Although the surface inflow is filamentary and the wind is episodic , we show the time averaged properties are well described by steady wind theory .
Even with strong fields , \beta _ { 0 } = 10 ^ { 3 } at the midplane initially , only 5 % of the angular momentum transport is driven by the wind , and the wind mass flux from the inner decade of radius is only \sim 0.4 % of the mass accretion rate .
( 4 ) Within the disk , most of the accretion is driven by the R \phi stress from the MRI and global magnetic fields .
Our simulations have many applications to astrophysical accretion systems .