School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA;Amoco Research Laboratory, Tulsa, Oklahoma 74102, USA;School of Applied and Engineering Physics, Cornell University, Ithaca, New York 14853, USA
Abstract:
Summary. Structural features of the Earth's lower crust and upper mantle can be mapped by the analysis of temporal geomagnetic fluctuations using the electromagnetic scattering theory developed in this paper. Decomposing geomagnetic field fluctuations at the Earth's surface into an excitation part and a scattered part forms the basis of a power series development. The vertical field component is interpreted as a scattering of the excitation field. The horizontal gradient and geomagnetic depth sounding methods are special cases of the theory developed. The horizontal gradient sounding method has a tensorial aspect which has not been recognized before; it should be included to obtain correct penetration depth parameter evaluations from field data.