Green's function retrieval by cross‐correlation in case of one‐sided illumination

The cross‐correlation of acoustic wave fields at two receivers yields the exact Green's function between these receivers, provided the receivers are surrounded by sources on a closed surface. In most practical situations the sources are located on an open surface and as a consequence the illumination of the receivers is one‐sided. In this Letter we discuss the conditions for accurate Green's function retrieval for the situation of one‐sided illumination. It appears that the Green's function retrieval method benefits from the fact that the earth is inhomogeneous, without relying on assumptions about disorder.