Potential fields known at a set of points can be expressed at neighboring higher or lower spatial locations in a source free region using the continuation integral that results from one of Green's theorems (see, e.g., Blakely, 1995). The principal uses of this concept are to adjust altitude of observations to a datum as an aid to the interpretation of a survey (see Crustal magnetic field), reduce short‐wavelength data noise by continuing the field upward, and increasing the horizontal resolution of anomalies and their sources by continuing the field downward. It is possible to continue the field upward or downward in a number of different ways depending on the application at hand; for example, designing continuation operators in spatial or wavenumber space (Henderson and Zietz, 1949; Dean, 1958), using harmonic functions (Courtillot et al., 1978; Shure et al., 1982; Fedi et al., 1999), and deriving physical property variations of sources causing the fields (Dampney, 1969; Emilia, 1973;...
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Ravat, D. (2007). Upward And Downward Continuation. In: Gubbins, D., Herrero-Bervera, E. (eds) Encyclopedia of Geomagnetism and Paleomagnetism. Springer, Dordrecht. https://doi.org/10.1007/978-1-4020-4423-6_311
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