Downward Continuation of Potential Fields within the Quasi-harmonicRegion

Downward continuation is a useful transformation, mainly used to enhance the measured field. Known limitations regard its instability and are theoretical, because the continuation level should not be deeper than the source depth. Despite of this downward continuation was used in several papers to recover source parameters with different methods here referred to as Normalized Full Gradient methods. These studies show that downward continuation may be applied to quasi-harmonic regions, i.e., volumes containing one-point isolated singularities. We modify the Normalized Full Gradient by using statistically meaningful normalizations and find improved, more resolved depth estimations. We show also that methods defined theoretically in the harmonic region, can still be meaningful when applied to downward continued fields within quasi-harmonic regions.