Sound as a tool for mapping conditions in the Arctic Ocean?

Today we welcomed students from Amalie Skram High School. The students are taking the subject Technology and Research Studies, and they are very interested in ocean technology.

The Nansen Center’s research is a perfect fit for students wanting insight into little-known applications of ocean technology. Senior researcher Hanne Sagen, who leads the Acoustics and Oceanography group, researcher Astrid Stallemo, and guest researcher Lora Van Uffelen (University of Rhodes Island, USA) gave the students an introduction to what the group does during research cruises to the Arctic Ocean.

The students got a crash course in what sound actually is, how sound propagates in water, and why sound is an important tool for measuring temperature in the inaccessible Arctic Ocean below the ice. They also learned about the instruments used to transmit and receive sound signals. It’s not just humans that emit sound in the ocean! The students also listened to sounds from earthquakes and different sounds from marine mammals such as whales and dolphins, which sound very different! Astrid told us about the UAK summer school she attended on board the coast guard ship KV Svalbard. The ship took the students to the Arctic Ocean, north of Svalbard. Hanne told the students about a new EU project that we are leading (HiAOOS), where researchers will use sound under the ice to “help” floating instrument buoys to navigate, using what is called “acoustic positioning”. This works in the same way as GPS does on land, using triangulation. In the ocean, however, sound waves are used instead of radio waves.

Lora introduced the students to how researchers handle large amounts of acoustic data, collected from the ocean over long periods of time. Since there is no time to listen to all these recordings, the sound is converted into so-called spectrograms. This is a visual representation of the frequencies that appear in a sound file, and the different frequencies are much easier to analyze than a complex sound file. In addition to the actual research work, logistics are an important part of the work when using ocean technology in the Arctic Ocean. The students also learned about the work behind the collection of such data: Planning, deployment, and retrieval of instrument rigs can be very demanding in Arctic conditions.

The students showed great interest in the scientists’ stories and appreciated seeing examples of the instruments used. They also asked the researchers many questions. The course they are taking at Amalie Skram High School is set up so that the students themselves will build buoys with sensors that can measure temperature, salinity and the like, and they will learn all about the use, calibration, deployment, and data analysis of sensors. In April, the buoys will be deployed, and the students are looking forward to getting started on the project. “It was exciting to hear about how we at the Nansen Center use different sensors to research conditions in the ocean,” the students said. Hopefully we have inspired some of them to see how exciting the field of ocean technology is!

Photo 1: Lora and Astrid explain how the hydrophone works.

Photo 2: Hanne shows how we send sound 2700 km over the Arctic Ocean to measure temperature.

Photo 3: Lora showcases different sounds and their spectrograms.

The HiAOOS project

The Arctic Ocean is an exciting area for researchers. Nowhere else is climate change happening faster, and increased knowledge is important if we are to understand the consequences of this. To get better information about the ocean under the ice, new technologies will be developed in the project “High Arctic Ocean Observation System“. Read more on the project website.