Sea ice rheology from in-situ, satellite and laboratory observations: Fracture and friction

On the basis of an analysis of in-situ ice stresses and of satellite-derived ice strain rates, as well as of a comparison between field and laboratory behaviour, we describe an alternative viewpoint for modelling sea ice deformation during winter. We propose that fracture and frictional sliding govern inelastic deformation over all spatial and temporal scales, even under small stresses. Consequently, winter and/or perennial sea ice does not behave as a viscous material, even at large scales, the normal flow rule is not obeyed (as observed during laboratory tests on sea ice samples harvested from the field), and stresses are highly intermittent and poorly correlated spatially.