Summer 2014 began with relatively cool temperatures in the Arctic, and the storms and winds that can break up ice and increase melting were absent, according to NASA cryospheric scientist Walter Meier. However, the overall thinning of sea ice has made it more susceptible to melting. The 2014 melt season concluded in September with the sixth-lowest extent of ice measured in the modern satellite era.
Even in years that have similar ice extents, however, the line traced around the edge of the sea ice can take on different shapes. Factors like wind and even the topography of the sea floor have been shown to affect the location of the edge of Arctic ice.
The Operational Land Imager (OLI) on Landsat 8 acquired this image of a small section of the sea ice edge on June 21, 2014 (the first day of summer). The ice pictured here is located in the Amundsen Gulf, between Canada’s Victoria Island and the mainland, and opens to the Beaufort Sea to the west. The gulf forms the westernmost side 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 edge shows the wide range of sea ice types often seen near the edge. Blue ice in the lower right corner of the image is older, thicker ice, which contains fewer and smaller pockets of air that cause the ice to primarily reflect blue light. Adjacent to the open water of the Amundsen Gulf is first-year ice, which grows over the course of just one winter. The dark grey ice is younger and thinner yet, 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 the first-year ice leaves the gulf along a westward route that follows the southern coast of Banks Island, while older ice from the Beaufort Sea enters the gulf along a path that follows the mainland’s coastline. The amount of ice exchanged between the Gulf and the Beaufort Sea in any given year depends on wind and the availability of space.
References
- 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 by Jesse Allen, using Landsat data from the U.S. Geological Survey. Caption by Kathryn Hansen.
- Instrument(s):
- Landsat 8 - OLI
