Cross-correlation of shipping noise: Refraction and receiver-motion effects

Area of Science:

• Ocean acoustics
• Seismic interferometry
• Wave propagation

Background:

• Diffuse noise fields theoretically contain time-domain Green's function (TDGF) information.
• Oceanic shipping noise is a dominant, non-uniform low-frequency noise source.
• Reconstruction of TDGF via cross-correlation is sensitive to source distribution and propagation.

Purpose of the Study:

• To investigate the influence of non-uniform noise source distributions and oceanic propagation conditions on TDGF reconstruction.
• To evaluate the impact of receiver motion on the cross-correlation procedure for obtaining TDGF from shipping noise.

Main Methods:

• Implementation of a wave-theoretic scheme to simulate noise fields.
• Modeling of cross-correlation functions for arbitrary noise source distributions in refractive environments.
• Analysis of simulated data to assess TDGF retrieval efficiency.

Main Results:

• The spatial distribution of noise sources significantly impacts TDGF reconstruction accuracy.
• Oceanic propagation conditions (e.g., refractive environments) affect the fidelity of the retrieved TDGF.
• Receiver motion can influence the efficiency and reliability of the cross-correlation method.

Conclusions:

• Reliable TDGF reconstruction from oceanic shipping noise requires careful consideration of source distribution and propagation effects.
• The developed wave-theoretic scheme provides a tool for studying noise field dynamics and seismic interferometry in complex environments.
• Further research is needed to optimize cross-correlation techniques for real-world oceanic noise conditions.