Arctic drilling is a controversial subject. From the array of tweets at #savethearctic there is a focus on environmental pollution and ice roaming animals. For instance, Greenpeace activist Mary Sweeters (@MSweeters) has this week tweeted about the carbon impact. There are other risks, however, to marine animals and those working on drilling platforms.
One of the dangers with the Arctic expansion projects, to boats, is with submerged icebergs and drift ice can. Thanks to new advances in sonar, vessels in the area will soon be able to “hear” ice formations and take measures to avoid a collision.
The new adaption of sonar has been developed by the Norwegian company Kongsberg. The utilization of sonar involves placing a fixed array of sensors some 200 meters below the surface of the sea. This will allow boats to deploy sonar to listen for ice on the move. Currently, most ice formations are tracked using satellites, with information transmitted back to vessels.
Sonar (SOund Navigation And Ranging) is an established technique that uses sound propagation (usually underwater) to navigate, communicate with or detect objects on or under the surface of the water. The focus on a single object limits the technology; however the Norwegian approach of using multiple sensors (or sonar heads) provides a far larger tracking field. The multibeam sonar heads have an array of transducers that simultaneously transmits pings (that is, sound pulses) at a specified frequency. These can cover a large area in less time than a single beam transducer.
The new technology can track ice at a distance of up to 1,200 meters and it operates at a frequency of between 10 and 15 kilohertz. It is this frequency that has raised some concerns from environmentalists. Some marine mammals are very sensitive to sonar frequencies, especially within the operating range of the new sonar system.
Interviewed by New Scientist magazine, bioacoustician Christopher Clark, from Cornell University in Ithaca, New York notes: “A 10-15 khz chirp is right in the sweet spot of most dolphins and whales. It’s another thing that adds to the clutter.” Clark is calling for a greater assessment of the use of sonar in the region in order to protect marine animals.
