Comparing modeled and measured sound levels from a seismic survey in the Canadian Beaufort Sea

Abstract

In this paper, we compare airgun sound levels measured during an offshore seismic survey to acoustic model predictions. The survey occurred in deep water (>650 m), on and beyond the continental slope in the Canadian Beaufort Sea. The modeling was performed with JASCO Applied Sciences' Marine Operations Noise Model, which uses a parabolic-equation-based algorithm to predict N×2 D sound propagation in ocean environments. Sound levels were measured with up to five calibrated Autonomous Multichannel Acoustic Recorders at distances of 50 to 50,000 m from the airgun array in water depths between 50 and 1,500 m. The sound levels were measured in both the broadside (across-track) and endfire (along-track) directions. The high-resolution digital recordings of seismic sounds were analyzed to determine peak and root-mean-square sound pressure levels and sound exposure levels as functions of range from the airgun array, and compared to the model results. Although the modeled sound levels were generally conservative, the model results accurately predicted the existence of a shadow zone and the overall transmission loss trend.