Varied forms of ice appear in these images from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor on NASA’s Aqua satellite and the Advanced Land Imager (ALI) on NASA’s Earth Observing-1 (EO-1) satellite. These natural-color images both show parts of the Mawson Coast, where an Australian-led research station is located. The MODIS image (from Dec. 16, 2011) offers a wide-area view, and the ALI image (Dec. 30, 2011) gives a close-up centered around the research station.
Near the shore, wet snow sits on the fast ice, and the water-saturated snow appears gray. Adjacent to that wet snow and on land lies a patch of blue ice, composed of large ice crystals. Wind in this region has eaten away the overlying snow layer to expose pure ice below. In contrast to tiny snow crystals, which appear white, large ice crystals absorb a small amount of red light, so greater amounts of green and blue reflect off the surface.
Descending warm winds evaporate snow cover and lead to strong surface melting on fast ice. As the Antarctic summer continues, the fast ice will break away from the coast and drift out to sea.
The close-up view also reveals some details of the coastline, including glaciers that calve icebergs at or near the coast, and isolated melt ponds on the surface of the blue ice.