  We study the diffusion of ocean waves by ice bodies much smaller than a
wavelength, such as pancakes and small ice floes. We argue that inhomogeneities
in the ice cover at scales comparable to that of the wavelength significantly
increase diffusion, producing a contribution to wave attenuation comparable to
what is observed in the field and usually explained by viscous effects. The
resulting attenuation spectrum is characterized by a peak at the scale of the
inhomogeneities in the ice cover, which could explain the rollover of the
attenuation profile at small wavelengths observed in field experiments. The
proposed attenuation mechanism leads to the same behaviors that would be
produced by a viscous wave model with effective viscosity linearly dependent on
the ice thickness. This may explain recent findings that viscous wave models
require a thickness-dependent viscosity to fit experimental attenuation data.
Experimental validation is carried out using wave buoy attenuation data and
synthetic aperture radar image analysis.
