NZ firm rides knowledge wave
A marine research company in Taranaki, New Zealand, claims it has achieved a world first in creating a new computer-based system that predicts what are known as long wave conditions.
ASR Marine Consulting and Research has developed the forecasting system, called MetOcean, to help client Port Taranaki better manage the efficiency and safety of port operations.
Now the company is claiming that there is huge potential for the system to be used by other ports around the world particularly those on western seaboards that are more exposed to big and energetic swells.
The claim is supported by Port Taranaki's operations manager Captain Ray Barlow, who says MetOcean will be a big help in efficient mooring of big ships in all weather conditions.
The port already has in place a computer-based system called Dynamic Under Keel Clearance (DUKC) which uses information on the draughts of ships, how much cargo the ships are carrying, the port depth, tides, and forecast weather and sea conditions to calculate when it is safe for vessels to arrive and depart.
MetOcean will be invaluable in adding new information on the long waves, helping make the DUKC even more efficient, says Captain Barlow.
Long waves known as infragravity waves are generated as part of normal wave action processes, and are created from the energy developed when waves break at or near the shore.
For this reason they occur at a lesser frequency than the normal waves, often being more than a minute apart. They are common within harbour areas such as Port Taranaki, and depending on the sea conditions outside the harbour - storm conditions and a high tide being the biggest contributors - they can cause a surge as high as 25cm.
When that happens, special mooring configurations need to be used so that no damage is caused to ships or the wharves they are tied up to.
While the existence of long waves has always been known, the MetOcean system is able to precisely predict when they will happen.
The system is the result of a special 100-day study into the relationship between wave energy outside Port Taranaki's harbour and the infragravity wave heights at the port's berths. Using those observations, ASR developed a numerical formula that makes the predictions.
Apart from its assistance for shipping movements at Port Taranaki, the new MetOcean forecast system also has the capability to provide another service - high-resolution predictions of wave and wind conditions in coastal regions.
ASR does this by obtaining the latest information about current and predicted wave conditions in the deep ocean around New Zealand, and combining it with wind forecasts to produce what the company calls a nowcast (a prediction of current conditions) and a five-day forecast of wave conditions.
The heart of the system is the numerical model that calculates the ways in which waves are generated, transformed and dissipated in response to changing ocean floor depths and the action and direction of the wind.
All that means that MetOcean is able to nest the forecasting for particular areas of coastline. This is useful for a wide range of potential users, from surfers and anglers, to boaties and even the offshore oil and gas industry.
Earlier this week, ASR representatives used MetOcean to forecast that on Thursday the swell at Cape Egmont would be between 2m and 3m, but that at Urenui the swell would be less than 1m.
"You simply can't get that sort of information from an ordinary forecast because it is so generalised," said ASR oceanographer Dr Peter McComb. "But we can make our predictions on a much smaller scale."
ASR will be taking MetOcean to Europe in July, where it will make a presentation to an oceanography conference in Madrid. It is confident this will lead to international use.
The Dominion Post