Isotopic and fluorescent tracers have been shown to provide
data on the rates and pathways of meltwater transport in the
summer pack-ice environment.
In particular during the first half of the ablation season,
substantial lateral transport of meltwater takes place in the
uppermost ice layers and within ponds at characteristic
length/time scales of several m/hr. Owing to the low permeability
of the underlying ice, runoff of meltwater and hence the area and
depth of melt ponds is controlled by the density and size of
conduits or permeable zones.
The linkage between permeability, pore size and advective heat
transfer in the ice cover results in a positive feedback that
increases discharge through high-permeability zones.
The localized discharge (through cracks and holes) as well as
seepage through permeable zones (bottoms of melt ponds) leads to
formation of underwater ice and false bottoms, locking substantial
amounts of freshwater for at least part of the melt season.
Desalination of level sea ice is controlled by vertical and
lateral percolation of freshwater from above and below, often
associated with substantial heat transfer and internal ice melt.