Paper Summary
A whole-space Greens function framework for the representation of the acoustic wavefield is obtained from the Helmholtz wave equation. Under this framework, the wavefield is represented by a distribution of pointsources in space and time, each corresponding to an elementary spherical wavefront. Intuition suggests the number of equivalent point sources actually required to represent the wavefield of interest might be small compared to the total number of speculative locations. Consequently, in spite of the problems innate ill conditioned nature, a satisfying solution can still be obtained by means of sparsity promotion. When a solution is reached, the wavefield can be reconstructed at new or existing locations by utilizing the framework in a forward modelling sense.