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Issue Two 2013 - Issue #19

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Smooth Sailing

Story by Mandy Thoo

View articles in related topics: Ocean Engineering, Sustainability & The Environment

edward linacre

By 2050 many ships will be able to cross the Arctic’s ‘northern route’ that connects Europe and Asia. For the first time, research is being conducted into how waves behave in these ‘new’ seas to help pave the way for safer travel. Arctic ice is melting at an accelerating rate – ice-covered areas of the Arctic Ocean in August 2012 have shrunk to 4.1 million square kilometres, the lowest extent ever recorded.

Driven by rising temperatures, half of the Arctic Ocean, which is roughly the size of Russia, was free of ice in the 2012 summer. These seas are also freezing 20 days later in the autumn compared to 30 years ago.

 To help facilitate less risky passages for tourist, research and naval ships, as well as fishing vessels, scientists at Swinburne’s Centre for Ocean Engineering, Science and Technology (COEST) have embarked on a five-year study of wave climate in the Arctic seas. Funded by the US Office of Naval Research, the project is focused on the Chukchi and Beaufort seas that lie north of Alaska.

Open seas, rising waves
Arctic waters will remain ice-free for longer each year, and shipping and energy companies are racing to take advantage, says Professor Alexander Babanin, head of the study and director of COEST, which specialises in the research of ocean waves, air-sea interactions, environmental extremes, climate and maritime engineering. “The open waters allow regular ships to take the shortcut to Europe or Asia, and also offer more access to oil and gas under the Arctic Ocean floor,” says Professor Babanin.

While this leads to opportunities for faster navigation and more fuel resources, Professor Babanin explains that a clear ocean also results in bigger, more powerful waves, followed by storm surges and coastal erosion. But currently, few geophysical and mathematical models can predict how these waves will behave. “We know little about the wave heights, periods, directions, as well as the frequency and duration of possible storms in the Arctic,” Professor Babanin says. “This is because wind waves in some of the Arctic seas are a completely new phenomenon and there are no studies of wave climates in this area.

To provide accurate forecasts for the safety of people who pass through this region, it’s crucial that we understand wave characteristics.”

When waves meet ice
Currently in its first year, the research includes studying the past decade’s satellite observations of Arctic waves, working on wave models and carrying out laboratory experiments on wave–ice interactions. “In theory, you could find out how the waves behave from available satellite observations,” Professor Babanin says. “But first we have to filter out the ice as it provides inaccuracies, and even then, we can’t use these results in statistics that are used to forecast waves. “Wind patterns and ice fields in the Arctic Ocean change constantly, and so will the corresponding waves.” Waves behave very differently in the presence of ice, as does ice in the presence of waves, Professor Babanin explains. The research team’s experiments have shown that ice floes – chunks of floating sea ice – scatter and dissipate waves, restricting how far the waves travel into the ice-covered ocean. At the same time, the waves can break up the ice, causing it to melt faster. “In order to predict future climate, we need wave models that take into account what happens when they meet the remaining ice fields and broken ice floes in the marginal zones.”

Modelling behaviour
Once they confirm the principles of these wave–ice interactions, the researchers plan to develop a physical model to forecast Arctic waves in the long and short term. In the meantime, they have submitted a proposal to build the first wave–ice flume in Australia together with the University of Melbourne, the University of Adelaide and the University of Newcastle. “We need a better understanding of the wave–ice physics before we travel to the Arctic in 2015 to carry out field experiments,” says Professor Babanin. “The wave–ice flume, equipped with a freezer and a wave-maker, will provide a realistic model of icy seas.” “Using fully coupled models, involving waves, sea ice, the ocean and the atmosphere, will help improve forecasting capabilities and climate predictions, including modelling the retreat of Arctic sea ice,” says Dr Luke Bennetts at the University of Adelaide, a research collaborator.

“Our research will also benefit the modelling of Antarctic sea ice, which has no land to protect it from the open ocean. This means that large waves can propagate up to hundreds of kilometres into the ice-covered ocean and break the ice as they travel.” “Arctic seas, presently covered with ice, are gradually opening,” Professor Babanin says. “Understanding the dynamics of the waves and their interactions with ice in such circumstances is crucial for ocean engineering, meteorological and oceanographic forecast in these significant areas of the world ocean.” L Wave expert Professor Alexander Babanin, remains fascinated with the elusive and temperamental waves even after studying them for 30 years.

“This is one of the most complex phenomena in nature, and it’s an interesting and challenging topic,” he says. “Everything that’s connected to the ocean is affected by waves, which is why they’re an important subject.” With stints as a research scientist in Russia, followed by the Australian Defence Force Academy and the University of Adelaide, Professor Babanin now works on projects that include incorporating waves into tropical cyclone and climate models, updating the physics of wave forecasts and studying infra-gravity waves (long-period oceanic waves that are kilometres long).

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