Philippe Mansuy

Experimental studies of the viscoplasticty of ice and snow

Polar ice sheets are fundamental elements of the climate system. Their extent and elevation have a direct influence on the global atmospheric circulation (through the albedo and wind intensity and direction) while the fresh water input from ice shelves and icebergs influence the ocean circulation. Furthermore the paleoclimatic records found in the deep ice cores drilled in polar ice sheets are an important source of information on the Earth climate mechanisms. As regards valley glaciers, as found in alpine regions, because they are very sensitive to temperature fluctuations they are nowadays considered as key indicators of present climate change. A good estimate of ice sheets mass balance response to climate change is needed to understand past sea level changes, while the mass balance of alpine glaciers is directly connected to present sea level rise. In this context it is very important to model the slow flow of glaciers and ice sheets, and to do so as well as possible, to improve our knowledge on the mechanical properties of ice. On the other hand, a wide range of engineering problems involve ice and snow mechanics, many of which in the high velocity or/and strain rate regimes (as for instance ice-structure interaction or snow avalanches). Since these later topics are exposed in other contributions to this book (see e.g. E. Schulson and M. Schneebeli) we will restrict ourselves to the very slow deformation of ice and snow in what glaciologist call the “viscoplastic regime”.