Acoustic propagation as an indicator of mesoscale oceanographic features in the Beaufort Sea

Intrusion of Pacific Summer Water (PSW) and Pacific Winter Water (PWW) into the Arctic Ocean through the Bering Strait leads to the formation of an acoustic duct in the Beaufort Sea. The Beaufort duct is characterized by PSW atop the colder PWW, which itself is colder than the deep polar water beneath. Decades of observation have shown that the Beaufort duct is a persistent and intensifying feature in the Beaufort Sea, with sound propagating hundreds of kilometers under the Arctic ice without ice or seabed interactions. However, fluctuations in its strength were observed during the 2016–2017 Canada Basin Acoustic Propagation Experiment (CANAPE), which suggest a breakdown of the duct between the acoustic sources and receivers. In this study, we review tomographic signals transmitted by the CANAPE sources from the Beaufort Sea received by arrays along the Chukchi Shelf break and analyze how the strength of those receptions can serve as temporal and spatial indicators of mesoscale oceanographic features such as eddies.