The Soundscape of the Southern Ocean – How Quiet and how Loud can Nature be?

• Main Authors: Kindermann, Lars, Boebel, Olaf, van Opzeeland, Ilse
• Format: Conference Object
• Language: unknown
• Published: Scientific Committee on Oceanic Research (SCOR) 2011
• Subjects: Antarc*; Antarctic; Antarctica; Ice Shelf; Ice Shelves; Iceberg*; Sea ice; Southern Ocean
• Online Access: https://epic.awi.de/id/eprint/31798/; https://epic.awi.de/id/eprint/31798/1/IQOE_Kindermann.pdf; http://www.scor-int.org/IQOE/Program_Book-1.pdf; https://hdl.handle.net/10013/epic.40523; https://hdl.handle.net/10013/epic.40523.d001

The Southern Ocean around the Antarctic continent provides some of the most extreme environmental conditions on earth which shape also the unique underwater soundscape. The area probably contains the most quiet locations within the world's oceans but is also stage for some of the loudest natural events. It is still relatively void of anthropogenic noise and is one of the most important feeding grounds for great whales. However, comparatively little acoustic data exists from this region so far because the collection of acoustic recordings is hindered by logistic constraints associated with this remote region. Very Quiet The large cavities below the giant floating ice shelves of Antarctica are amongst the most isolated areas in the world - but with a window to the open sea. Neither local surface noise nor biological sources are present within hundreds of kilometers radius. Sound levels here should reflect unbiased readings of the long-range acoustic energy field - and yield a lower boundary of how quiet the ocean can get. During much of the year large parts of the polar oceans are covered by sea ice, which has a significant impact on the underwater acoustics. Sea ice isolates the water from the air, impeding the generation of waves, while the snow layer absorbs acoustic energy efficiently, creating an "anechoic chamber" which may serve as a natural lab to test and verify sound propagation models. Very Loud But ice is also a major source of noise. Table icebergs, calved from the shelf, are the largest moving objects on earth, spanning areas of 1000 square kilometers with a thickness of several hundred meters. Driven by the ocean currents, billions of tons of ice can gain terajoules of kinetic energy, equaling that of a nuclear bomb. This energy can be released within a brief period of time when the iceberg touches ground or collides with other bergs or the ice shelf. These events produce some of the loudest natural broadband sounds in the ocean, rivaled only by earthquakes and can be recorded in distances as far as ...