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Arctic melt ponds form when meltwater clogs ice pores: Pond formation mechanism previously unknown
http://unews.utah.edu/melt-ponds/[font face=Serif][font size=5]Arctic melt ponds form when meltwater clogs ice pores[/font]
[font size=4]Pond formation mechanism previously unknown[/font]
Jan 24, 2017
[font size=3]When spring comes to the Arctic, the breakup of the cold winter ice sheets starts at the surface with the formation of melt ponds. These pools of melted snow and ice darken the surface of the ice, increasing the amount of solar energy the ice sheet absorbs and accelerating melt. A team including University of Utah mathematician Kenneth Golden has determined how these melt ponds form, solving a paradoxical mystery of how a pool of water actually sits atop highly porous ice. Their results are published in Journal of Geophysical Research – Oceans.
“Here we’re presented with this fundamental puzzle,” Golden says. “How in the world do you form ponds? When they form, how deep they are, and their areal extent is absolutely critical for how the ice is going to melt.”
…
“The freezing point of the fresh meltwater from snow is zero Celsius,” Golden says. “But the ice itself is maybe -1 or -1.5. The freezing point of seawater is -1.8. So basically, you’re getting this infusion of fresh water and there’s enough cold there to clog up the pores. You’re lowering the permeability of the ice by this process of freezing freshwater plugs into the porous microstructure.” With lowered permeability, the meltwater can form a pool on top of the ice.
Others, including Polashenski, had speculated that such a process might be behind melt pond formation, Golden says, but that his team was in the right place at the right time with the right equipment to put the story together in the field. Hopefully, he says, understanding the conditions that lead to melt pond formation can help scientists predict where and when ponds might form as Arctic temperatures continue to rise.
…[/font][/font]
http://dx.doi.org/10.1002/2016JC011994
[font size=4]Pond formation mechanism previously unknown[/font]
Jan 24, 2017
[font size=3]When spring comes to the Arctic, the breakup of the cold winter ice sheets starts at the surface with the formation of melt ponds. These pools of melted snow and ice darken the surface of the ice, increasing the amount of solar energy the ice sheet absorbs and accelerating melt. A team including University of Utah mathematician Kenneth Golden has determined how these melt ponds form, solving a paradoxical mystery of how a pool of water actually sits atop highly porous ice. Their results are published in Journal of Geophysical Research – Oceans.
“Here we’re presented with this fundamental puzzle,” Golden says. “How in the world do you form ponds? When they form, how deep they are, and their areal extent is absolutely critical for how the ice is going to melt.”
…
“The freezing point of the fresh meltwater from snow is zero Celsius,” Golden says. “But the ice itself is maybe -1 or -1.5. The freezing point of seawater is -1.8. So basically, you’re getting this infusion of fresh water and there’s enough cold there to clog up the pores. You’re lowering the permeability of the ice by this process of freezing freshwater plugs into the porous microstructure.” With lowered permeability, the meltwater can form a pool on top of the ice.
Others, including Polashenski, had speculated that such a process might be behind melt pond formation, Golden says, but that his team was in the right place at the right time with the right equipment to put the story together in the field. Hopefully, he says, understanding the conditions that lead to melt pond formation can help scientists predict where and when ponds might form as Arctic temperatures continue to rise.
…[/font][/font]
