Modeling challenges in near-shore acoustic transmission: A multi-year measurement study

Over the past 3 years, we have conducted multiple field campaigns to investigate long-range atmospheric acoustic transmission in a coastal environment. The primary measurement site, located along the western shore of Roanoke Island in eastern North Carolina, enabled controlled pitch-catch experiments with an acoustic source and multiple microphone arrays positioned up to 2 km away. Acoustic data were collected concurrently with detailed meteorological measurements, including wind profiles, temperature gradients, humidity, and surface conditions over both land and water paths. This unique dataset spans a wide range of environmental conditions including varying wind and temperature profiles during sunrise, sunset, daytime, and nighttime conditions, as well as varying surface states such as uniform vegetation, calm water and wind-driven waves. Results reveal significant variability in measured transmission related to refractive effects of near-surface wind and temperature gradients, with noted impacts from surface transitions and localized turbulence. Measurements are compared with numerical predictions from a Crank–Nicholson parabolic equation solver with site-specific meteorological inputs. These comparisons highlight both the predictive capability and limitations of current modeling approaches in near-shore environments.