A joint oceanography and acoustics experiment was conducted on the Washington continental shelf in the summer of 2022. A towed system measured the in situ sound speed field along a 20 km track between acoustic sources and receivers. A weak but persistent subsurface duct was found with its sound speed minimum generally in the 50–100 m–depth range. The duct exhibited range and time dependence due to the internal tide, internal waves, and possibly other oceanographic processes. Mid-frequency (3500 and 6000 Hz) transmission loss (TL) was measured at 10 and 20 km ranges. The subsurface duct has a 10–13 dB effect on TL, depending on whether the sound source is inside or outside the duct. Measurements were also made using a bottom-mounted source, with transmissions every 3 min over several days. The sound intensity varies about 10 dB over a few minutes, while the scintillation index fluctuates between 0.5 and 1.5. Overall, it is found that mid-frequency sound propagation is variable at several temporal scales, ranging from minutes to hours, to days, or longer. Reducing the impact of these variabilities in acoustic applications would benefit from knowledge of the ocean processes at these different time scales.

Wind and pressure fields associated with a tropical cyclone are the primary driving atmospheric forcing for storm surge computations. Here, performance of various atmospheric forcing during an Extremely Severe Cyclonic Storm Hudhud of Bay of Bengal (BoB) in computing storm surges and wave characteristics are evaluated with observations. Atmospheric forcings considered are obtained from parametric wind models of Holland, reanalysis data -ERA5, and a fully physics-based weather prediction model-WRF. Study utilises ADvance CIRCulation (ADCIRC) model in standalone as well as tightly coupled with, Simulating WAves Nearshore (ADCIRC + SWAN) for generating storm surge and wave characteristics, respectively. Peak water levels at landfall are well computed when forced by parametric wind model than ERA5 or WRF. Also, ADCIRC + SWAN, resulted in an additional wave-set up ranging from 0.05 m to 0.35 m with different atmospheric forcing. Furthermore, study revealed that, both standalone ADCIRC and coupled ADCRIC + SWAN model predicted storm surge levels better when forced with 1980 Holland wind model. However, significant wave heights were better simulated by ADCIRC + SWAN with WRF forcing. This study aims to assess the capabilities of various atmospheric forcing methods employed in the BoB for the prediction of storm surges and waves, in addition to providing valuable insights for further improvement.