  Observations in polarized emission reveal the existence of large-scale
coherent magnetic fields in a wide range of spiral galaxies. Radio-polarization
data show that these fields are strongly inclined towards the radial direction,
with pitch angles up to $35\degr$ and thus cannot be explained by differential
rotation alone. Global dynamo models describe the generation of the radial
magnetic field from the underlying turbulence via the so called
$\alpha$-effect. However, these global models still rely on crude assumptions
about the small-scale turbulence. To overcome these restrictions we perform
fully dynamical MHD simulations of interstellar turbulence driven by supernova
explosions. From our simulations we extract profiles of the contributing
diagonal elements of the dynamo $\alpha$-tensor as functions of galactic
height. We also measure the coefficients describing vertical pumping and find
that the ratio $\hat{\gamma}$ between these two effects has been overestimated
in earlier analytical work, where dynamo action seemed impossible. In
contradiction to these models based on isolated remnants we always find the
pumping to be directed inward. In addition we observe that $\hat{\gamma}$
depends on whether clustering in terms of super-bubbles is taken into account.
Finally, we apply a test field method to derive a quantitative measure of the
turbulent magnetic diffusivity which we determine to be ~ 2 kpc kms.
