Elimination of edge effects in potential‐field data processing by equivalent source technique

S U M M A R Y Edge effects are distortions at the edge of a domain which are artifacts of the implicit assumptions of a numerical algorithm or of the limited span of data used to solve the problem (Sheriff, 1991, p. 96). During wavenumber domain filtering of potential-field data, (e.g., reduction to the pole, pseudogravity, and directional derivative, etc.), edge effect distortions are usually parallel to the boundaries of the data set. Amplitudes of these artifacts could be several times the maximum amplitude of the real anomalies in the data. A conventional processing method results in distortion of up to twenty-five percent of the data points. We use an approach developed by Xia et al. (1993) for determining equivalent sources and then calculating specific anomalies based upon these equivalent sources. A synthetic example shows that edge effects are reduced to a negligible level when the reduced-tothe-pole operator is applied to magnetic anomalies. We also apply the reduced-to-the-pole operator to aeromagnetic data in Kansas, which gives a satisfactory result