Bearing estimation and 2D localization of bowhead whale calls using directional autonomous seafloor acoustic recorders.
ABSTRACT Passive acoustic monitoring of the summer/fall westerly bowhead whale migration in the Beaufort Sea has been conducted by Greeneridge Sciences, sponsored by SEPCO, every year since 2006. The directional autonomous seafloor acoustic recorder (DASAR) packages used in this effort each contain three acoustic sensors that simultaneously measure the two horizontal components of acoustic particle motion and acoustic pressure. A variety of data-adaptive beamforming methods have been applied to a selected subset of these data to examine direction-of-arrival estimation performance, including quantifying bearing bias and variance. A principal component analysis (PCA)-type eigenanalysis of the sensor data cross spectral matrix is used to decompose the received field into orthogonal components having different particle motion polarization and energy flux properties. Appropriate manipulation of these components provides high resolution directional estimates of the primary arriving energy while maintaining robustness to uncertainties in sensor calibration and acoustic propagation conditions. Representative results of beamforming as well as 2D localization performance will be presented. Application of data-adaptive beamforming techniques to bulk processing of these large monitoring data sets will be discussed. [Work supported by Shell Exploration and Production Company (SEPCO).].