Meltwater circulation and permeability of Arctic summer sea ice derived from hydrological field experiments

Permeability and meltwater flow have been studied in sea ice in the Siberian and central Arctic during the summers of 1995 and 1996. A bail-test technique has been adapted to allow for measurements of in situ permeability, found to range between 10 and 10 m. Permeability varied by about a factor of 2 between 1995 (above-normalmelt rates) and1996 (below-normalmelt rates). Release of fluorescent tracers (fluorescein, rhodamine) furthermore allowed the derivation of flow velocities and assessment of the relevant driving forces. Hydraulic gradients in rough ice andwind stress in ponded ice were found to be particularly important, driving meltwater over distances of several meters per day.The midto late-summer ice was found to be permeable enough to completely divert meltwater from the surface into the ice interior. It is shown, however, that lower permeabilities of the upper ice layers as well as refreezing of meltwater, particularly during the early melt season, foster the development of surface melt ponds.