July is the peak of melt season in the Arctic. The sun is high and shines for almost 24 hours a day. Air and water temperatures rise above freezing. Rapid midsummer melt is therefore both unremarkable and unsurprising. But it is also an unreliable indicator of just how much ice will cover the Arctic Ocean when the September annual sea ice minimum arrives. Now a combination of satellite and on-the-ice observations are helping scientists better understand summer sea ice behavior and track the evolution of melt ponds atop the ice, so as to more accurately forecast what extent will remain frozen at the September minimum. In separate research, scientists have recently demonstrated how to see details on sea ice, combining high- and low-resolution satellite images to get a clearer picture of melt ponds and thereby test how well climate models are capturing melt pond evolution. Scientists study Arctic melt pond evolution. Image courtesy of Melinda Webster, University of Washington. Uncovering melt ponds with satellites Ice and snow reflect sunlight, keeping the Arctic cool, while large dark areas of open ocean absorb abundant solar energy, which triggers more ice melt and delays the autumn refreeze. Melt ponds sitting atop the sea ice absorb more energy than fresh snow, but less than open water. So, understanding their evolution could help scientists better forecast future seasonal sea ice extent. But melt ponds have always been hard to see — especially on satellite images. Passive microwave data can’t distinguish between melt ponds and open…This article was originally published on Mongabay
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