Inside a deep ice core. From small scale processes to large scale flow

A deep ice core extracted from a polar ice sheet contains information about small scale deformation and microstructure evolution processes, and, in the meantime, informs us about large scale flow processes surrounding it. Polar ice caps initiate from snow falling on the surface, snow then compact to become ice, that deforms while flowing to the edges. All along these multi-physics processes, ice grains (or crystals) are moving their boundaries, changing shape, orientation, leading to the evolution of the ice flow properties. Climate signal is being impregnated into this ice, and flowing history leaves its mark too. How do we build the link between scales? What do we learn from Earth and Material Sciences to understand ice, and what can ice tell us about fundamental mechanisms? During this presentation, I will show some characteristics of polar ice and snow physical properties as extracted from a deep ice core, and I will illustrate the laboratory observations and experiments performed to better understand some processes that come into play, namely densification and dynamic recrystallization.