The science team and crew aboard the Norwegian Coast Guard Vessel (NoCGV) Svalbard have successfully recovered a network of moorings from the deep and ice-covered Nansen and Amundsen Basins of the Arctic Ocean. Over the past two years, the moorings have collected data that will provide new insights into the ocean beneath the sea ice.
The network, developed through a collaboration between the Nansen Environmental and Remote Sensing Center and Scripps Institution of Oceanography, is one of the most extensive observing systems ever deployed in the ice-covered Arctic Ocean. The moorings have collected measurements of ocean temperature, salinity, ocean currents, sea-ice conditions, and underwater sound in the waters north of Svalbard. These observations will provide valuable new insights into ocean conditions in one of the least-observed regions on Earth.
Acoustic signals transmitted between the moorings make it possible to measure variations in the speed of sound in the ocean. These measurements can be converted into estimates of average ocean temperature over vast areas, in this case across the Nansen and Amundsen Basins. This method is known as acoustic thermometry. Traditional oceanographic measurements represent conditions at a single location, while acoustic thermometry yields an average temperature over hundreds of kilometers. It offers valuable insight into large-scale ocean variability and change.
The moorings also carry instruments that measure salinity, ocean currents, sea-ice conditions, and underwater sound from marine mammals, vessel traffic, and seismic activity. Together, these observations constitute one of the most comprehensive datasets ever collected from the ice-covered Eastern Arctic Ocean.
At the same time, the network demonstrates how acoustic signals can be used for navigation and precise positioning beneath sea ice. This technology could enable the expansion of the so-called “Argo Programme” into ice-covered regions through tracking of profiling floats and support navigation of autonomous underwater vehicles measuring ocean conditions at different depths, in areas where GPS signals are unavailable. This opens new opportunities for future observing and research operations in the Arctic Ocean.
“These observations are valuable not only because they help improve existing ocean models, but because they provide a direct measure of the present-day state of the Arctic Ocean beneath the sea ice. To determine whether the changes we observe are part of long-term climate trends or natural variability, we need continuous measurement records spanning many years. Long-term monitoring beneath the sea ice is essential for understanding and predicting the future evolution of the conditions in the Arctic Ocean and what effects these conditions have on the global climate system.” – says Hanne Sagen, HiAOOS Project Coordinator, at the Nansen Environmental and Remote Sensing Center.
The successful operation is the result of outstanding efforts of Captains Einar Overå and Geir-Martin Leinebø, the crew and conscripts aboard KV Svalbard, together with a broad international scientific partnership. This collaboration has made it possible to conduct long-term observations in one of the world’s most remote and operationally challenging marine environments.
Read more about the details of the mooring system and the collaboration around it on the HiAOOS project page.
Key researchers: Hanne Sagen, Espen Storheim, Vår Dundas, Stein Sandven
