Calorimetric in-situ determination of ice water content in two Alpine glaciers

Abstract. Temperate glacier ice contains liquid water at different concentrations. How much exactly depends on the history of ice formation, the heat supply from dissipative deformation, and on the drainage pathways between ice crystals. The interstitial liquid water content strongly influences the ice viscosity and therefore glacier flow speed. The hydrological system of glaciers is strongly affected by the porosity of the ice matrix. Also, material properties, such as seismic velocities, electromagnetic susceptibility and dielectricity are strongly affected. This renders seismics and radar suitable to measure water content in a glacier. An independent in-situ method is a calorimetric determination by tracking an artificially induced freezing front within the material. Here, we report on two experiments from an artificial cave within a glacier and form a tunnel at the base of a glacier. In both experiments, a liquid water content of 1–2 % was found by analyzing the measured cooling rates with a detailed numerical model of the experimental setup.