ARCHIVED - Unique Canadian Technology Helps Forecast Dangerous Iceberg Drifts

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March 07, 2007— Ottawa, Ontario

On the Atlantic Ocean's Grand Banks southeast of Newfoundland a frozen, blue-tinged giant, the size of a 15-storey building and weighing 200 thousand tons is slowly drifting south — towards one of the world's largest off-shore oil rigs. A collision would be an environmental and economic catastrophe. Will the mega-ice cube hit? A unique iceberg drift computational model developed by National Research Council (NRC) scientists and partners is giving those in the icebergs path an unprecedented ability to judge the odds, and stay out of harms way.

"Bergy Bits": blocks of ice ranging in size from two-to-15 metres in length. Photo courtesy of Dr. Michelle Johnston.

The Grand Banks is rich in both oil and ice – a dangerous combination. There are three producing off-shore oil platforms on the Grand Banks: Hibernia which stands on the ocean floor; and Terra Nova and White Rose, both floating platforms. These off-shore oil platforms are in the bulls eye of Iceberg Alley, the route travelled by icebergs calved primarily from glaciers on Greenland's west coast and propelled south by the Labrador current.

"The icebergs are the main environmental risk for the oil platforms and the shuttle tankers that transport the crude to shore," says Garry Timco, group leader, Cold Regions Technologies, for the NRC Canadian Hydraulics Centre (NRC-CHC). "Predicting an iceberg's drift is extremely important to these industries. And it's also extremely difficult to predict."

With the development of the offshore and oil and gas industry on the Grand Banks in the 1980s a sophisticated iceberg monitoring and management industry has developed, led by the Environmental Services Division of St. John's-based Provincial Aerospace. The challenge is to determine which individual icebergs pose the threat of a direct hit. Icebergs that are considered on a collision course with rigs are towed onto a safe course.

The NRC-CHC Iceberg drift forecasting tool is the computational equivalent of a grand master snooker player - able to line-up a ball and its target with exacting accuracy. Except that in this case it's a meandering giant ice crystal tugged this way and that by currents, winds and waves.

Map of Grand Banks.

The first Canadian technology of its kind, the iceberg drift model was developed collaboratively by NRC-CHC research scientists Mohamed Sayed and Ivana Kubat, McGill University professor Stuart Savage, and Tom Carrieres of the Canadian Ice Service (CIS). Funding for the research was from Natural Resources Canada's Program of Energy Research and Development (PERD).

"When iceberg watchers identify an iceberg they think is threatening, they call into the CIS with its location and estimated waterline length. The data is put into the model and within ten minutes they get the iceberg's drift forecast," says NRC-CHC research scientist Ivana Kubat, who's developing the latest versions of the model.

Using the equations that describe the physics of motion, the forecast model mathematically simulates the various environmental forces that determine an iceberg's drift. These include the iceberg's size, the swell height and the prevailing wind and currents. The drift model, which is run on a desk-top PC, was validated by comparing it against actual observations of iceberg drift around Hibernia.

"This new model is at least 30% better than the existing model we're using and there's room for even more improvement as we integrate in more accurate models of current flow," says Tom Carrieres, CIS's Ice Modelling Manager. He says that the key improvement is the ability to include complex ocean currents in the new model. Currents at depths of about 10 metres have been shown to be a key factor in determining an iceberg's path.

Carrieres notes that the CIS works very closely with the International Ice Patrol (IIP), a division of the U.S. Coast Guard established in the wake of the Titanic disaster. The two organizations share all their iceberg data, and at present still use the IIP iceberg drift model as the default model for iceberg drift forecasting.

"The IIP model has worked very well for many years, now it's our job to thoroughly demonstrate that this new model is more accurate in all cases," notes Carrieres.

Based on requests from end users, Kubat has developed a new, simplified "on-board", or local iceberg forecasting model. Presently being tested by users, the model can be used by ships captains or pilots to quickly calculate an iceberg's trajectory using local environmental conditions.

Figure showing modelled and observed drift of an iceberg over a 14-hour period.
Figure showing modelled and observed drift of an iceberg over a 14-hour period.

The NRC-CHC iceberg drift model is also the first of its kind to predict iceberg calving and the resulting size distribution and drift of "bergy bits" - blocks of ice ranging in size from two-to-15 metres in length. For example, the model is able to predict the number of calved bergy bits larger than two metres.

"This is essential information for the shuttle tankers," says Kubat. "Based on knowing where the bergy bits are they can adjust their course to avoid a collision course and potential damage to the ship."


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