A new class of filter transfer function derived from Wiener filter and Green’s equivalent layer principles is presented for upward and downward‐continuation enhancement of potential‐field data. The newly developed transfer function is called the preferential continuation operator. In contrast to the conventional continuation operator, the preferential continuation operator possesses a continuation response that acts preferentially upon a specific band of the observed potential field’s Fourier amplitude spectrum. The transfer function response approaches the response of an all‐pass filter away from this band. This response characteristic is useful for at least two common potential‐field signal enhancement applications. First, it is possible with preferential upward continuation to attenuate shallow‐source, short‐wavelength, potential‐field signals while minimally attenuating deep‐source, long wavelength signals (as often happens after application of conventional upward continuation) Second, it is possible with preferential downward continuation to enhance deep‐source, long wavelength signals without overamplifying shallow‐source, short‐wavelength signals (as often happens after application of conventional downward continuation) Preferential continuation, used qualitatively for anomaly enhancement, ably overcomes these two limitations of conventional continuation enhancement.
Extension for Downward Continuation of the Method of "Upward Continuation of Potential Field on Spherical Patch Area"
