Waveform inversion of ambient noise cross-correlation functions in a coastal ocean environment

Abstract

Approximations to Green's functions have been obtained by cross-correlating concurrent records of ambient noise measured on near-bottom instruments at 5 km range in a 100 m deep coastal ocean environment. Inversion of the measured cross-correlation functions presents a challenge as neither ray nor modal arrivals are temporally resolved. We exploit both ray and modal expansion of the wavefield to address the inverse problem using two different parameterizations of the seafloor structure. The inverse problem is investigated by performing an exhaustive search over the relevant parameter space to minimize the integrated squared difference between computed and measured correlation function waveforms. To perform the waveform-based analysis described, it is important that subtle differences between correlation functions and Green's functions are accounted for. [Work supported by NSF and ONR.]