Techniques are disclosed relating to the determination of a warping attribute related to a difference between an up-going pressure wavefield and a down-going pressure wavefield received from a seismic data acquisition system. The warping attribute is used to determine a pseudo up-going or down-going pressure wavefield. The pseudo pressure wavefield is used to generate a modified record of geophysical data, which is stored in a non-transitory memory medium as a geophysical data product.