We examine the effects of density stratification on magnetohydrodynamic turbulence driven by the magnetorotational instability in local simulations that adopt the shearing box approximation .
Our primary result is that , even in the absence of explicit dissipation , the addition of vertical gravity leads to convergence in the turbulent energy densities and stresses as the resolution increases , contrary to results for zero net flux , unstratified boxes .
The ratio of total stress to midplane pressure has a mean of \sim 0.01 , although there can be significant fluctuations on long ( \gtrsim 50 orbit ) timescales .
We find that the time averaged stresses are largely insensitive to both the radial or vertical aspect ratio of our simulation domain .
For simulations with explicit dissipation , we find that stratification extends the range of Reynolds and magnetic Prandtl numbers for which turbulence is sustained .
Confirming the results of previous studies , we find oscillations in the large scale toroidal field with periods of \sim 10 orbits and describe the dynamo process that underlies these cycles .