Effect of bottom topography on sound propagation near the Atlantis II seamount

This work investigates through a modeling exercise how and how much capturing the details of the bathymetry matter for establishing the physical environment in which sound propagates. Two simulations are considered, one with a realistic bathymetry of the New England Seamount region (NESM run) and a second with a single Gaussian seamount of comparable width and height to the Atlantis II seamount (SEAMOUNT run). Both runs are submesoscale permitting (1 km horizontal resolution) with 100 vertical levels. The idealized SEAMOUNT simulation captures a broad range of physical phenomena modeled by the NESM run including a mixed barotropic-baroclinic mechanism responsible for topographic eddy generation, and bottom boundary layer (BBL) separation on the anticyclonic side arising from an overturning instability when the North Atlantic Current flows atop Atlantis II. The scattering of internal waves from the small-scale rough bottom topography and consequent vertical mixing is however underestimated in the idealized SEAMOUNT run. Internal waves can cause attenuation of the propagating sound waves due to acoustic mode coupling. We discuss how dynamical processes like internal waves affect sound propagation near the Atlantis II seamount.