Acoustics in an integrated Arctic Ocean Observing System in Fram Strait

The Fram Strait is a main gateway for heat exchange between the Arctic and Atlantic Oceans, hence estimating the heat transport is important to understanding the on-going climate change in the Arctic. The Strait has been monitored with oceanographic moorings since 1996, but the small scale and complex oceanographic processes in this region make it difficult to get accurate measurements of the heat transport. To improve the estimates of the transport, one needs to combine in situ measurements with high resolution ocean models. A multipurpose acoustic observing system was designed to complement the oceanographic point measurements made by the oceanographic mooring array crossing the Strait. Synoptic large-scale measurements of mean ocean temperature have been derived from acoustic thermometry and used to evaluate the results from ocean models with different vertical and horizontal resolutions. Building on the results from this work, the assimilation of acoustic measurements into ice-ocean models is under development.

Year-long measurements of ocean sound from different geographical positions at a number of depths were also obtained from the acoustic observing system. The ocean soundscape is influenced by climate-related changes in the Arctic. Therefore, these acoustic measurements will provide important background for future environmental assessments and sound management in this region.