Quantcast

Huge Waves Measured For The First Time In Arctic Ocean

July 31, 2014
Image Caption: The sea ice in July 2014 as it begins to retreat from the Alaskan coast. Credit: J. Thomson / UW

Hannah Hickey, University of Washington

As the climate warms and sea ice retreats, the North is changing. An ice-covered expanse now has a season of increasingly open water that is predicted to extend across the whole Arctic Ocean before the middle of this century. Storms thus have the potential to create Arctic swell – huge waves that could add a new and unpredictable element to the region.

A University of Washington researcher made the first study of waves in the middle of the Arctic Ocean, and detected house-sized waves during a September 2012 storm. The results were recently published in Geophysical Research Letters.

“As the Arctic is melting, it’s a pretty simple prediction that the additional open water should make waves,” said lead author Jim Thomson, an oceanographer with the UW Applied Physics Laboratory.

His data show that winds in mid-September 2012 created waves of 5 meters (16 feet) high during the peak of the storm. The research also traces the sources of those big waves: high winds, which have always howled through the Arctic, combined with the new reality of open water in summer.

Arctic ice used to retreat less than 100 miles from the shore. In 2012, it retreated more than 1,000 miles. Wind blowing across an expanse of water for a long time creates whitecaps, then small waves, which then slowly consolidate into big swells that carry huge amounts of energy in a single punch.

The size of the waves increases with the fetch, or travel distance over open water. So more open water means bigger waves. As waves grow bigger they also catch more wind, driving them faster and with more energy.

Shipping and oil companies have been eyeing the opportunity of an ice-free season in the Arctic Ocean. The emergence of big waves in the Arctic could be bad news for operating in newly ice-free Northern waters.

“Almost all of the casualties and losses at sea are because of stormy conditions, and breaking waves are often the culprit,” Thomson said.

It also could be a new feedback loop leading to more open water as bigger waves break up the remaining summer ice floes.

“The melting has been going on for decades. What we’re talking about with the waves is potentially a new process, a mechanical process, in which the waves can push and pull and crash to break up the ice,” Thomson said.

Waves breaking on the shore could also affect the coastlines, where melting permafrost is already making shores more vulnerable to erosion.

The observations were made as part of a bigger project by a sensor anchored to the seafloor and sitting 50 meters (more than 150 feet) below the surface in the middle of the Beaufort Sea, about 350 miles off Alaska’s north slope and at the middle of the ice-free summer water. It measured wave height from mid-August until late October 2012.

> Explore Further…


Source: Hannah Hickey, University of Washington



comments powered by Disqus