Arrival-time structure of the time-averaged ambient noise cross-correlation function in an oceanic waveguide

Area of Science:

• Acoustics
• Seismology
• Wave Propagation

Background:

• Ambient noise cross-correlation is a technique used to infer Earth's structure.
• Experimental observations have confirmed coherent arrival times in various environments.
• Existing formulations of ambient noise cross-correlation lack detailed source distribution analysis.

Purpose of the Study:

• To demonstrate a method for extracting coherent deterministic arrival times from ambient noise.
• To analyze the influence of noise source distribution and receiver bandwidth on arrival times.
• To compare derived formulations with existing methods for ambient noise cross-correlation.

Main Methods:

• Utilizing a time-domain image formulation of the noise cross-correlation function.
• Analyzing a uniform distribution of noise sources within a Pekeris waveguide.
• Investigating the derivative of the time-averaged ambient noise cross-correlation function.

Main Results:

• Coherent deterministic arrival times can be extracted from the derivative of the noise cross-correlation function.
• The image formulation reveals the impact of noise source distribution (range and depth) on arrival times.
• Receiver bandwidth significantly influences the arrival-time structure.

Conclusions:

• The study provides a clear demonstration of extracting deterministic arrival times from ambient noise.
• The developed image formulation offers a practical tool for analyzing noise cross-correlation data.
• Findings have direct implications for interpreting data from oceanographic and seismic experiments.