Exploiting the Spatio-Temporal Coherence of Ocean Ambient Noise for Passive Tomography.

摘要

Coherent processing of ambient noise, based on these computed noise cross-correlation between receivers, has been suggested as a potential means for developing passive methods for ocean acoustic tomography or thermometry (Roux et al., 2004). However, this technique can require long recording times to extract stable coherent arrivals from ocean noise correlations (Sabra et al., 2005a; Godin, 2010). Array beamforming can enhance the emergence of such deterministic arrivals between receiver arrays. For instance, a single vertical array was used to improve passive imaging of seabed layers (Siderius et al., 2010; Siderius, 2011; Traer and Gerstoft, 2011). The main objective of this year research was to develop a general spatiotemporal filtering STF technique to enhance the emergence rate of coherent wavefronts between two spatially separated receiver arrays. The performance of this STF technique was demonstrated using ocean ambient noise recordings dominated by non-stationary shipping noise to monitor the arrival-time fluctuations of coherent noise wavefronts over a six day long observation time.