Contextualizing single-hydrophone measurements from autonomous platforms in the Arctic

Upper ocean sound-speed structure in the Arctic is highly sensitive to climate change and sea ice variability, yet remains poorly observed, particularly under ice. Low-frequency sound sources transmitting across the Arctic deployed as part of the High Arctic Ocean Observing System (HiAOOS) offer a unique opportunity to obtain measurements of acoustic signals at long range and therefore integrated ocean temperature under water and under ice across the Arctic Ocean. Autonomous buoyancy platforms equipped with hydrophone receivers are well-suited for receiving these signals, offering low self-noise except during brief pumping operations. The mobility and persistence of autonomous platforms also make them valuable tools for collecting in situ measurements of the temporal and spatial structure of ocean sound-speed, which is critical for interpreting received acoustic data. Interpreting data from a single hydrophone remains challenging; however, predictions of acoustic propagation incorporating in situ oceanographic measurements can be used to contextualize single-hydrophone data collected on these buoyancy platforms for identification and classification of acoustic arrivals. Preliminary results from a buoyancy float deployed from the KV Svalbard in August 2025 will be presented. This work aims to advance autonomous acoustic sensing capabilities under water and under ice in polar regions.