  The arrival directions of multi-TeV cosmic rays show significant anisotropies
at small angular scales. It has been argued that this small-scale structure can
naturally arise from cosmic ray scattering in local turbulent magnetic fields
that distort a global dipole anisotropy set by diffusion. We study this effect
in terms of the power spectrum of cosmic ray arrival directions and show that
the strength of small-scale anisotropies is related to properties of relative
diffusion. We provide a formalism for how these power spectra can be inferred
from simulations and motivate a simple analytic extension of the
ensemble-averaged diffusion equation that can account for the effect.
