Meltwater Penetration Through Temperate Ice Layers in the Percolation
Zone of the Greenland Ice Sheet
Abstract
Meltwater retention in the firn layer of the Greenland Ice Sheet is has
the potential to buffer sea level rise due to ice sheet melt. The
capacity of the firn layer to store meltwater is unclear, however,
because refrozen ice layers can act as impermeable barriers to meltwater
percolation, promoting runoff rather than retention. We present
time-domain reflectometry and thermistor data which demonstrates that
meltwater successfully penetrates ice layers up to 12 cm thick in the
near-surface firn at Dye2, Greenland. Our observations indicate that ice
layers within polar firn can become permeable when summer warming and
latent heat release from refreezing meltwater raise temperatures to the
melting point. This facilitates meltwater retention, and indicates that
the depth of penetration of the summer melting front (the 0°C isotherm)
represents the primary control on meltwater infiltration in the
percolation zone of the Greenland Ice Sheet.