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Dartmouth Researchers Analyze Data From Arctic Expedition

Nov 09, 2020   |   NHPR

"[The Multidisciplinary Drifting Observatory for the Study of Arctic Climate, known as] MOSAiC was 10 years in the planning, and it was motivated by an overarching science question: what are the causes and consequences of an evolving and diminished Arctic sea ice cover? And what that question is really saying is there have been tremendous changes over the past few decades in the Arctic sea ice cover, and in fact, it serves as an indicator of global climate change. And we wanted to go up and spend a year drifting with the ice to take a series of observations to help us first, observe the changes, and then understand them," said Professor Donald Perovich in a recorded interview about the largest ever Arctic expedition with NHPR's Morning Edition.

... "A couple of people say, well, gee, now that MOSAiC's over, what are you going to do with your life? Well, the fun is just beginning. I mean, this incredible data set will be studied for decades. And at this stage, the first task is for us to analyze our data, do quality control and get it into an archive. From the very beginning, we've recognized with MOSAiC that the data are the legacy of the project, and we want to make this data accessible as possible to a wider group of scientists as we can and also to convey what we learned to the general public."

... "We're a sea ice team and we're looking at a few key questions. One, we want to understand the snow on sea ice. And just a quick primer, it's so cold in the Arctic Ocean that the ocean freezes forming sea ice. And this ice cover is maybe 5 to 10 feet thick. And during part of the year, it's covered by snow. We want to understand how deep that snow is, how it moves around and what its impact is on ice growing in the winter and melting in the summer.

"Another task we had was to try to understand a concept called the mass balance of the ice. And that's just simply how much does it grow in the winter and how much does it melt in the summer? And in particular, how much of it melts on the surface of the ice and how much melts on the bottom the ice? And that allows us to attribute whether these changes that we observe in the ice are being driven mainly by the atmosphere, or by the ocean or both.

"And finally, the third element of our project. Well, it was one of my favorites, and that was to study what happens to sunlight. Of the incoming sunlight, how much gets reflected by the ice cover, how much gets absorbed in the ice and how much gets transmitted into the ocean? And if we look at snow covered ice, it's a great reflector. It reflects around 85 percent of the sunlight. If we look at the ocean, it's a poor reflector. It reflects less than 10 percent of the sunlight. And so changes between ice in the ocean can have a feedback, where as you expose more ocean, you put more sunlight absorbed, you get more melting, you expose more ocean. And that was one of the key things we wanted to look at, because you need to be able to treat that feedback properly in models."

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