A method according to one aspect for deghosting seismic data includes determining wave heights in an area wherein marine seismic data have been acquired by actuating a seismic energy source in a body of water and detecting seismic energy at each of a plurality of spaced apart seismic receivers deployed in the water. A reflectivity distribution function of the water surface is determined using the determined wave heights. A ghost function is determined from the reflectivity distribution function. The ghost function is applied to the marine seismic data to deghost the marine seismic data. In other embodiments, the reflectivity distribution function may be used to invert notional source signatures from near field seismic energy or modeling/attenuation free-surface multiples for both land and marine seismic data.