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PostPosted: Thu Apr 04, 2013 8:51 am
 


NASA satellite witnesses Arctic ice sheet being torn to shreds

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NASA's Suomi NPP polar-orbiting weather satellite captured dramatic footage of an 'extensive fracturing event' in the Arctic ice sheet this winter, and the scale of this event is causing some concern.



The time-lapse video compresses down over two months worth of observations into just over a minute, to show the full magnitude of the event.

The fracturing started in late January, as a warm-weather system over Alaska fed an ocean current known as the Beaufort Gyre. This strengthened current picked away at the southwest corner of the ice sheet until a massive crack opened up north of central Alaska (at about 3 secs into the video), and then another crack, apparently around 1,000 kms long, opens up in late February (at around 30 sec in the video), leading to the collapse of the rest of the ice sheet, all the way east to Bank Island.

“It took just seven days for the fractures to progress across the entire area from west to east,” Trudy Wohlleben, senior ice forecaster at the Canadian Ice Service, told the National Post.

According to Walt Meier, a research scientist with the National Snow & Ice Data Center (NSIDC), it's not unusual for this area to experience fracturing events. However, what is unusual is the extent of the fracturing and the scale (both length and width) of the cracks being seen, and it's the age of the ice that's being blamed.

“The region is covered almost completely by seasonal or first-year ice — ice that has formed since last September,” said Meier, according to the NASA Earth Observatory article. “This ice is thinner and weaker than the older, multi-year ice, so it responds more readily to winds and is more easily broken up.”

Last September saw the lowest extent of Arctic sea ice since records began in 1979. The sea ice rebounded by record levels over the winter (only because it dropped to such a record low, though), reaching its maximum extent on March 15th. However, even that was still the sixth-lowest sea ice extent on record, and this year's melt has started nearly two weeks before last year's.

With this much of the Arctic ice sheet fracturing this soon into the seasonal melt, it can't bode well for what minimum extent we'll see in the fall. The ice didn't disappear, of course, but with more dark ocean water being exposed this early, that will lead to higher Arctic ocean temperatures and more melting. So, we could set an even lower record minimum this year.


http://ca.news.yahoo.com/blogs/geekquin ... 53074.html


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PostPosted: Thu Apr 04, 2013 9:12 am
 


8O 8O


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