The characteristics and formation of a high-arctic proglacial icing

Well-known from permafrost hydrology, icings (naled or Aufeis) are also frequently encountered at the margins of high-latitude glaciers. The morphology of a proglacial icing at Scott Turnerbreen in the Norwegian Arctic archipelago of Svalbard is described, and the process of formation is considered in detail. Ground thermal-regime modelling indicates an equilibrium permafrost depth of at least 200 m in the studied catchment, and it appears unlikely that groundwater contributes to icing formation. Meltwater flow through ice-marginal drainage channels is accompanied by estimated heat fluxes of up to about 190 W m−2, suggesting that stored meltwater may continue to percolate through thawed sub-channel sediments when surface runoff is absent during winter. A hydraulic conductivity of 6.9 × 10−3 m s−1 is implied, which is consistent with other studies of glacier drainage systems. The long residence time of winter-draining meltwater, and solute rejection by refreezing water, account for high observed concentrations of solute in interstitial water in the icing. It has often been asserted that the presence of a proglacial icing indicates that a glacier is polythermal. However, as Scott Turnerbeen is entirely non-temperate, the presence of an icing cannot always be treated as a reliable guide to the thermal regime of a glacier.