Today's story is part of our recent feature series Landsat Goes Over the Top: A Long View of the Arctic.
The summer of 2014 began with relatively cool temperatures in the Arctic, and the storms and winds that can break up ice were mostly absent, according to NASA ice scientist Walt Meier. But the long-term thinning of sea ice has made it more susceptible to melting, so the 2014 melt season concluded with the sixth-lowest ice extent of the modern satellite era.
Even in years with similar ice extents, the line traced around the edge of the sea ice can take on different shapes. Factors like winds and even the topography of the sea floor can affect the location and extent of Arctic ice.
The Operational Land Imager (OLI) on Landsat 8 acquired this image of an interesting sea ice edge on June 21, 2014, the first day of summer. The scene shows a part of the Amundsen Gulf, between Canada’s Victoria Island and the mainland, that opens to the Beaufort Sea to the west. The gulf forms the westernmost section of the Northwest Passage, which opened during the low-ice year of 2007, but remained ice-bound in 2014.
The close-up view of the ice shows a wide range of sea ice types. Blue ice in the lower right corner is thicker ice that is several years old; it contains fewer and smaller pockets of air that would normally cause ice to reflect blue light. Adjacent to the open water of the Amundsen Gulf is first-year ice, which grows in just one winter. The dark grey ice is even younger and thinner, and might represent an area of recently open water that refroze. Finally, brash ice—wreckage of various ice types afloat in the water—is seen drifting in the gulf’s open water. Snow on top of the sea ice accounts for some of the white areas.
Researchers have shown that a large amount of first-year ice leaves the gulf along a westward route that follows the southern coast of Banks Island. Older ice from the Beaufort Sea enters the gulf along a path that follows the mainland coastline. The amount of ice exchanged between the Gulf and the Beaufort Sea in any given year depends on wind and the amount of open water.
- NASA Earth Observatory (2014, September 24) A Tale of Two Poles. Accessed March 6, 2015.
- National Snow & Ice Data Center (2014, July) Melting in the North, freezing in the South. Accessed March 6, 2015.
- Nghiem, S.V. et al. (2012, November 15) Seafloor control on sea ice . Deep Sea Research Part II: Topical Studies in Oceanography, 77-80, 52-61.
- Prinsenberg, S J. et al. (2013, March 19) Atmospheric control of sea-ice thickness variability in the Amundsen Gulf, Beaufort Sea, and over the Labrador Shelf. Annals of Glaciology, 54 (62).
- University of Washington (2015, March 3) On thin ice: Combined Arctic ice observations show decades of loss. Accessed March 6, 2015.
- Woods Hole Oceanographic Institution (2014, July) Edge of the Arctic Shelf: Sea Ice Glossary. Accessed March 6, 2015.
NASA Earth Observatory image (top) by Jesse Allen and Robert Simmon, using Landsat data from the U.S. Geological Survey and acquired by special request with the support of Theresa Arvidson (NASA/GSFC) and Eugene Fosnight (USGS/EDC). Caption by Kathryn Hansen.
- Landsat 8 - OLI