A Range-Dependent Analysis of Acoustic Transmission Across a Cold Filament in the California Current

Recurrent patterns in surface thermal fronts associated with cold filaments along the West Coast of North America

“…Applications of marine acoustics include, but are not limited to, navigation (e.g., Fasham, 1976), fish detection (e.g., Mitson, 1983;Hargreaves, 1975), naval operations (e.g., Jendro et al, 1991;Cheesebrough and Pittenger, 1991), oceanographic variability studies (e.g., Regier, 1982), acoustic telemetry for communications and control (e.g., Cattanach, 1970;Uscinski et al, 1989), and underwater survey (e.g., Roberts, 1971). This diverse set of marine applications has one very important aspect in common: They are all sensitive to variations in sound speed velocity (and hence acoustic index of refraction), which in turn are controlled by the vertical and horizontal distributions of water properties (i.e., temperature, salinity, and pressure), but most especially by temperature (Burdic, 1984).…”

“…For example, Jendro et al (1991) constructed sound speed profiles for a California Current filament and then used a range-dependent parabolic equation model to predict sonar ranges in a simulated naval exercise. Their results showed that the acoustic advantage between two adversaries changed as their position relative to the filament and to each other changed because temperature gradients as small as I°C/25 km were sufficient to determine whether or not CZ transmission occurs.…”