Embodiments of the present invention provide systems and methods for deriving a source signature for an array of seismic sources for marine seismic analysis, wherein the systems and methods include factors for determining the source signature taking into consideration both sea-surface and sea-floor reflections of signals produced by the seismic sources. In certain aspects, reflection coefficients of the sea-surface and the sea-floor and relative lengths of paths between a seismic source image and a detector are applied to a series of simultaneous equations that are solved using measurements of the pressure field produced by the array at a plurality of known locations to determine individual source signatures for each seismic source in the array and these individual source signatures may then be superposed to provide a source signature for the array that accounts for sea-floor reflections of outputs from the seismic sources.