Navigation in ships: PolarView
Safe navigation in ice covered seas is a uniquely challenging activity that is routinely undertaken in Antarctica by specially strengthened vessels. It can be slow and laborious and there is an ever present risk of besetment in the constantly shifting pack ice that surrounds the Antarctic continent.
Even without becoming trapped, ships are slowed considerably by sea ice. The ability to avoid the greatest concentrations of ice can save valuable days and allow scientists to be delivered to Antarctica sooner. It also reduces fuel and charter costs.
While the AAD has previously used satellite imagery to assist navigation through the sea ice, we have recently begun using a new system that enhances our capabilities.Known as PolarView, it is a product of the European Space Agency. Every day, satellites passing overhead collect radar and passive microwave images of the Antarctic sea ice.
These images have the advantage over photographs of penetrating the ever present cloud layer, giving a clear picture of the ice below. Using a number of automatic tools the images are converted into products that graphically illustrate the characteristics of the sea ice on a given day. These products are then distributed to sea ice scientists around the world by e-mail.
Adapting PolarView to support our needs has been a joint venture between the Sea and Air Operations section of the AAD and glaciologists in the Ice, Ocean, Atmosphere and Climate programme, based at the Antarctic Climate and Ecosystems Cooperative Research Centre. The glaciologists developed a browser that can be used to easily view and manipulate the PolarView products.
The process was trialled over three voyages of the RSV Aurora Australis in the 2006-07 season. The products were e-mailed directly from Europe to the ship, where the voyage leader could view them on the browser. The voyage leader was then able assess the ice conditions likely to be encountered, and therefore the best route to be taken. Back in Hobart, a rostered glaciologist received the same products and remained on call to receive any satellite phone calls from the voyage leader, to advise on an ice assessment if necessary.
Sea and Air Operations kept the PolarView team appraised of the ship's movement and, at critical points, satellites were tasked to take higher resolution images of key areas coinciding with the approach of the ship.
The trial was a great success. The Polarview products were easy to use when viewed with the browser and they accurately reflected the ice conditions encountered. The system enabled the ship to travel more efficiently than would have been previously possible.
We intend to use the system again in the International Polar Year, where it should have a significant effect, particularly on an early season sea ice research voyage.
While PolarView does not eliminate the risk of besetment or delay due to ice, it reduces that risk, and is likely to become a standard part of AAD shipping operations.
Article written be Sea & Air Operations Manager David Tonna