Investigating the effects of ocean layering and sea ice cover on acoustic propagation in the Beaufort Sea

Abstract

Over the past several decades, the Beaufort Gyre has experienced changes in sea-ice freshwater accumulation and ocean stratification which has implications for long-range acoustic propagation. In this talk, acoustic propagation from the Canadian Basin to the Alaskan Beaufort Shelf is modeled using measurements of physical oceanography and sea ice. Water masses that impact acoustic propagation and stratification in the basin include the warm, saline Atlantic Water (AW), which is overlain by cooler, less-saline Pacific Winter Water (PWW). Oceanographic observations reveal intrusions of a warmer, fresher water mass called Pacific Summer Water (PSW). This water mass resides below the surface mixed layer, but above the PWW and reduces acoustic interaction with the sea-ice canopy for source depths located in the halocline duct. Oceanographic data indicate that on the continental shelf, the PSW intrusion can be absent in the ice-covered months resulting in an upward refracting sound speed profile. Using measurements from ice-tethered profilers in the basin and oceanographic moorings on the shelf, we model the temporal and spatial variability of the acoustic field. The effect of scattering from the ice cover is included, with consideration given to the seasonal variability of sea-ice concentration, thickness, and acoustic properties.