Great Lakes Ice Cover Reached 88 Percent This Winter; Highest Levels Since 1994

In mid-February 2014, ice cover on the Great Lakes reached 88 percent, levels that have not been observed in 20 years.

Since 1973, the average maximum ice extend is just over 50 percent. It has surpassed 80 percent only five times over the course of the past four decades. The lowest average ice extent occurred in 2002, when just 9.5 percent of the Great Lakes froze over.

NASA recently released images of the frozen Great Lakes, which were acquired through the Moderate Resolution Imaging Spectroradiometer (MODIS) which is on NASA's Aqua satellite. The images were taken on February 19, 2014. The first one (above) shows the Great Lakes in natural color during the early afternoon, and the second, false-color image (below) uses a combination of shortwave infrared, near infrared, and red that help to distinguish ice from snow, water and clouds. In this image, the ice is pale blue with thicker ice being brighter, open water is navy blue, snow is blue-green, and clouds are either white or blue-green (depending on the temperature and their composition).

Nathan Kurtz, a cryospheric scientist at NASA's Goddard Space Flight Center, commented on the satellite images:

“Persistently low temperatures across the Great Lakes region are responsible for the increased areal coverage of the ice. Low temperatures are the dominant mechanism for thickening the ice, but secondary factors like clouds, snow, and wind also play a role.”

George Leshkevich of NOAA's Great Lakes chimed in, stating:

“We had an early ice season this year, owing to cold temperatures in the fall and early winter. Ice was reported on bays and harbors of the Great Lakes as early as the end of November, as opposed to the normal timing of mid-December.”