Sunday, February 23, 2014

NASA MODIS Image: US Great Lakes Frozen

The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Aqua satellite captured this image on Feb. 19, 2014. 

Credit: NASA

A deep freeze has settled in over the Great Lakes this winter and a new image released by NASA shows the astonishing extent of the ice cover as seen from space.

NASA's Aqua satellite captured this image of the lakes on the early afternoon of Feb. 19, 2014.

At the time, 80.3 percent of the five lakes were covered in ice, according to the Great Lakes Environmental Research Laboratory (GLERL), part of the National Oceanic and Atmospheric Administration (NOAA).

Earlier this month, ice cover over the Great Lakes hit 88 percent for the first time since 1994.

Typically at its peak, the average ice cover is just over 50 percent, and it only occasionally passes 80 percent, according to NASA's Earth Observatory.

A false colour image of the frigid Great Lakes on Feb. 19, 2014. 

Credit: NASA

Cold temperatures that have persisted in the region are largely responsible for this year's thick layer of ice, but cryospheric scientist Nathan Kurtz, of NASA's Goddard Space Flight Center, told the Earth Observatory that "secondary factors like clouds, snow and wind also play a role."

And some lakes are more frozen than others.

Nathan Kurtz
While the ice cover over Lake Erie, Lake Superior and Lake Huron is approaching 100 percent, Lake Ontario is only around 20 percent frozen and Lake Michigan is about 60 percent covered, according to the latest update from GLERL.

NASA researchers also put together a false-colour image combining shortwave infrared, near infrared and red wavelengths to pick out ice from other elements that look white in visible-wavelength images like snow, water and clouds. In this image, ice appears pale blue, and the thicker it is the brighter it looks.

Open water, meanwhile, is shown in navy, snow is blue-green and clouds appear either white or blue-green, according the Earth Observatory.

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