  We study energy dissipation and heating by supersonic MHD turbulence in
molecular clouds using Athena, a new higher-order Godunov code. We analyze the
dependence of the saturation amplitude, energy dissipation characteristics,
power spectra, sonic scaling, and indicators of intermittency in the turbulence
on factors such as the magnetic field strength, driving scale, energy injection
rate, and numerical resolution. While convergence in the energies is reached at
moderate resolutions, we find that the power spectra require much higher
resolutions that are difficult to obtain. In a 1024^3 hydro run, we find a
power law relationship between the velocity dispersion and the spatial scale on
which it is measured, while for an MHD run at the same resolution we find no
such power law. The time-variability and temperature intermittency in the
turbulence both show a dependence on the driving scale, indicating that
numerically driving turbulence by an arbitrary mechanism may not allow a
realistic representation of these properties. We also note similar features in
the power spectrum of the compressive component of velocity for supersonic MHD
turbulence as in the velocity spectrum of an initially-spherical MHD blast
wave, implying that the power law form does not rule out shocks, rather than a
turbulent cascade, playing a significant role in the regulation of energy
transfer between spatial scales.
