Abstract : It was shown in [Garnier et al., SIAM J. Imaging Sciences 2 (2009),
396] that it is possible to image re ectors by backpropagating cross correlations
of signals generated by ambient noise sources and recorded at passive sensor
arrays. The resolution of the image depends on the directional diversity of
the noise signals relative to the locations of the sensor array and the reflector.
When directional diversity is limited it is possible to enhance it by exploiting
the scattering properties of the medium since scatterers will act as secondary
noise sources. However, scattering increases the fluctuation level of the cross
correlations and therefore tends to destabilize the image by reducing its signal-
to-noise ratio. In this paper we study the trade-o in passive, correlation-based
imaging between resolution enhancement and signal-to-noise ratio reduction
that is due to scattering.