A method to minimize edge effects in two‐dimensional discrete Fourier transforms

Fourier transforms are widely used in analysis of two‐dimensional (2-D) earth‐science data, such as gravity and magnetic surveys, topographic models, and remote‐sensing images. For example, manipulations of gridded magnetic or gravity data, such as upward and downward continuation, reduction to the pole, wavelength filters, pseudogravity transformation, and vertical derivatives (Hildenbrand, 1983), are greatly simplified with Fourier transforms, as are certain forward and inverse calculations (Parker, 1973; Parker and Huestis, 1974). Power spectra computed from 2-D Fourier transforms are used to estimate depth to the top and bottom of magnetic sources from gridded magnetic data (Spector and Grant, 1970; Connard et al., 1983) and to estimate lithospheric strength and Moho depth from gridded gravity data (Dorman and Lewis, 1970; Louden and Forsyth, 1982; McNutt, 1983).