Methods and systems for marine survey acquisition

A method, comprising:

• deploying a marine seismic spread comprising:
• at least one streamer having at least one receiver;
• a first seismic source that is connected to and towed by a vessel;
• and
• a second seismic source that is connected to and towed by the vessel and is disposed at a distance from the first seismic source in an inline direction, wherein the distance is selected to produce one or more pairs of shot points during a seismic survey, wherein the shot points within a pair are disposed within a predetermined range that is configured to be used to calculate a pressure source gradient between the shot points within the pair;
• shooting the first seismic source and the second seismic source substantially simultaneously;
• recording seismic data associated with shooting the first seismic source and the second seismic source;
• and
• calculating the pressure source gradient for respective pairs of shot points, wherein calculating the pressure source gradient comprises determining a difference between wavefield measurements at the shot point locations for at least one of the respective pairs, and wherein the difference is determined with respect to a change in location between shot points in the at least one of the respective pairs.