  We develop a two-flow model of accretion onto a black hole which incorporates
the effect of the local magneto-rotational instability. The flow consists of an
accretion disk and an accreting corona, and the local dynamo affects the
disk/corona mass exchange. The model is aimed to explain the power spectrum
density of the sources in their soft, disk-dominated states. The local
perturbations of the magnetic field in the disk are described as in King et al.
(2004) and Mayer and Pringle (2005), but the time-dependent local magnetic
field is assumed to affect the local supply of the material to the corona.
Since the viscous timescale in the corona is much shorter than in the disk, the
local perturbations are not smeared in the corona. Simple analytical estimates
and full time-dependent computations of the disk-corona system are performed.
The accreting corona model can reproduce the broad power spectra of Soft State
X-ray binaries and AGN. The model, however, predicts that (i) sources
undergoing radiation pressure instability (GRS 1915+105) should have
systematically steeper power spectra than other sources, (ii) AGN should have
systematically steeper power spectra than GBH, even if their disks are
described using viscosity proportional to the gas pressure. More precise
measurements of power spectra of Soft State sources are clearly needed.
