In situ measurements of meltwater flow through snow and firn in the accumulation zone of the SW Greenland Ice Sheet

Abstract. The Greenland Ice Sheet is losing mass, part of which caused by increasing runoff. location the runoff limit, highest elevation from meltwater finds its way off ice sheet, plays an important role in surface mass balance sheet. recently observed rise area might be related to amount refreezing: layer development firn reduces vertical percolation and promotes lateral To investigate flow near limit accumulation zone on southwestern Sheet, we carried out situ measurements hydrological processes properties snow. hydraulic conductivity icy pre-melt conditions measured using a portable lysimeter ranges 0.17 12.8 m h?1, with predominantly occurring through preferential fingers. Lateral velocities top near-surface slab, at peak melt season salt dilution tracer experiments, range 1.3 15.1 h?1. With these velocities, distance between slush where liquid water visible sheet surface, could roughly 4 km regions slabs are present. These first step towards integrated set SW show evidence that may occur elevations above area.