  We use a relativistic ray-tracing code to calculate the light curves observed
from a global general relativistic magneto-hydrodynamic simulation of an
accretion flow onto a Schwarzschild black hole. We apply three basic emission
models to sample different properties of the time-dependent accretion disk.
With one of these models, which assumes thermal blackbody emission and
free-free absorption, we can predict qualitative features of the high-frequency
power spectrum from stellar-mass black holes in the "Thermal Dominant" state.
The simulated power spectrum is characterized by a power law of index Gamma ~ 3
and total rms fractional variance of <~ 2% above 10 Hz. For each emission
model, we find that the variability amplitude should increase with increasing
inclination angle. On the basis of a newly-developed formalism for quantifying
the significance of quasi-periodic oscillations (QPOs) in simulation data, we
find that these simulations are able to identify any such features with
(rms/mean) amplitudes >~ 1 % near the orbital frequency at the inner-most
stable orbit. Initial results indicate the existence of transient QPO peaks
with frequency ratios of nearly 2:3 at a 99.9% confidence limit, but they are
not generic features because at any given time they are seen only from certain
observer directions. Additionally, we present detailed analysis of the
azimuthal structure of the accretion disk and the evolution of density
perturbations in the inner disk. These "hot spot" structures appear to be
roughly self-similar over a range of disk radii, with a single characteristic
size \delta\phi=25 deg and \delta r/r=0.3, and typical lifetimes T_l ~ 0.3
T_orb.
