# Global acoustic daylight imaging in a stratified Earth-like model

## TL;DR

This paper analyzes acoustic daylight imaging in a stratified Earth-like model, showing how to recover eigenfrequencies and the scattering operator from surface measurements using autocorrelation functions.

## Contribution

It establishes a relation between autocorrelation functions of surface measurements and the scattered wave field, enabling eigenfrequency and scattering operator recovery.

## Key findings

- Eigenfrequencies can be recovered from autocorrelation.
- Complete scattering operator can be extracted under specific geometric conditions.
- Provides a theoretical foundation for acoustic daylight imaging in stratified media.

## Abstract

We present an analysis of acoustic daylight imaging in an Earth-like model assuming a random distribution of noise sources spatially supported in an annulus located away from the surface. We assume a situation with scalar wave propagation and that the measurements are of the wave field at the surface. Then, we obtain a relation between the autocorrelation function of the measurements and the trace of the scattered field generated by an impulsive source localized just below the surface. From this relation it is, for example, clear that the eigenfrequencies can be recovered from the autocorrelation. Moreover, the complete scattering operator can be extracted under the additional assumption that the annulus is close to the surface and has a thickness smaller than the typical wavelength.