The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired the top image of ice cover on North America’s Great Lakes on March 17, 2015. On that day, ice covered 55 percent of the lakes, according to the NOAA Great Lakes Environmental Research Laboratory. The bottom image shows ice cover a year earlier (March 16, 2014) when ice covered 75 percent of the lakes. Use the image comparison tool to see the difference.
Ice cover on the Great Lakes peaked at more than 80 percent in 2014 and again in 2015, marking the sixth such occurrence in four decades. The average maximum ice extent since 1973 has been about 50 percent.