From Bright Windows to Dark Spots: The Evolution of Melt Pond Optical
Properties during Refreezing
The evolution of melt ponds on Arctic sea ice has a large impact on the
surface energy balance and the ice-associated ecosystem. Melt ponds are
considered as bright windows to the ocean, because they transmit more
solar radiation into the ocean than bare ice, also during freeze-up.
Here we present results from under-ice radiation measurements close to
the North Pole during summer 2018 using a remotely operated vehicle in
combination with ice and snow measurements. Our results reveal that
light transmittance of melt ponds is lower compared to bare ice once
covered by the first snow. Results from a radiative transfer model
suggest that refrozen melt ponds with a snow cover (> 0.04
m) lead to lower light transmittance than adjacent bare ice. This has
implications on autumn ecosystem activity and thermodynamical ice
growth, because it reduces the solar heat input to the Arctic Ocean in
September by >50%.