UPPER MANTLE LATERAL INHOMOGENEITY ESTIMATED USING GLOBAL MVS
V.V. Plotkin, A.Yu. Belinskaya, P.A. Gavrysh
Institute of Petroleum Geology and Geophysics, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: Upper mantle; global MVS; lateral variations of Earth's electrical conductivity; mantle hot fields; spherical harmonic analysis
Pages: 616-625
Abstract
We processed synchronous observatory MVS data at periods from 1.2 to 6 days to estimate lateral conductivity variations in the upper mantle. The inverse problem for depth-dependent conductivity distribution was solved using correlation of the measured surface components of the geomagnetic field. We applied spherical harmonic expansion of the complex amplitudes of time harmonics and multiple averaging of the amplitudes obtained for different SH sets. The chosen approximation approach was tested by comparing the EM field simulated for a smoothly inhomogeneous Earth with the exact forward solution. The SHA-analyzed observatory data for fifteen magnetic storms were used to map global apparent conductivity variations.
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