What is An Ice Arch?

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An ice arch is a key patch of block ice that prevents other pieces of ice from entering a strait or other body of water. One such structure found every year is the ice arch that typically forms between Ellesmere Island and Greenland every January. While the ice arch is in place, typically for roughly six months out of every year, flowing ice is prevented from flowing through the Nares Strait. This narrow waterway which separates Greenland and Ellesmere Island, experiences a significant among of ice passing through it due to a southward flowing current, fueled by the Beaufort Gyre.

Arctic Ocean circulation. —Image courtesy of Arctic Monitoring and Assessment Programme (AMAP), Figure 3.29, AMAP (1998).
Arctic Ocean circulation. Map: courtesy of Arctic Monitoring and Assessment Programme (AMAP), Figure 3.29, AMAP (1998).

The Nares Strait ice arch typically crumbles in June or July each year although the breakdown has occurred usually early in some years such as the disintegration of the ice arch starting in March/April of 2019 and in May of 2017. Researchers believe the 2017 early ice arch collapse was due to “presence of a polynya in northern Nares Strait, thin ice in the Lincoln Sea, and an unusual wind regime characterized by strong northerly flow.”

In March the ice arch starting to disintegrate.  By April, satellite imagery was showing the crumbling of the ice pack behind the ice arch.  By May, sea ice was flowing freely through Nares Strait.  Images: NASA.
In March the ice arch starting to disintegrate. By April, satellite imagery was showing the crumbling of the ice pack behind the ice arch. By May, sea ice was flowing freely through Nares Strait. Images: NASA.

References

Hansen, K. (2019, June 25). Ice arch crumbles early. NASA Earth Observatory. https://earthobservatory.nasa.gov/images/145232/ice-arch-crumbles-early


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Moore, G. W. K., & McNeil, K. (2018). The early collapse of the 2017 Lincoln Sea ice arch in response to anomalous sea ice and wind forcing. Geophysical Research Letters45(16), 8343-8351. https://doi.org/10.1029/2018GL078428

Voiland, A. (2017, May 20). Breakdown of an ice arch. NASA Earth Observatory. https://earthobservatory.nasa.gov/images/90245/breakdown-of-an-ice-arch

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