TERRAPUB Earth, Planets and Space

Earth Planets Space, Vol. 65 (No. 11), pp. 1233-1237, 2013

Determination of the 1-D distribution of electrical conductivity in Earth's mantle from Swarm satellite data

Christoph Püthe and Alexey Kuvshinov

ETH Zürich, Institute of Geophysics, Sonneggstrasse 5, 8092 Zürich, Switzerland

(Received December 17, 2012; Revised July 17, 2013; Accepted July 22, 2013; Online published November 22, 2013)

Abstract: We present an inversion scheme to recover the (1-D) depth profile of mantle conductivity from satellite magnetic data, which takes into account 3-D effects arising from the distribution of oceans and continents. The scheme is based on an iterative inversion of C-responses, which are estimated from time series of the dominating external (inducing) and internal (induced) spherical harmonic coefficients of the magnetic potential due to a magnetospheric source. These time series will be available as a Swarm Level-2 data product. We verify our approach by using synthetic, but realistic time series obtained by simulating induction due to a realistic magnetospheric source in a 3-D ``target'' conductivity model of the Earth. This model contains not only a laterally heterogeneous layer representing oceans and continents, but also 3-D inhomogeneities in the mantle. The inversion for mantle conductivity is initiated with a uniform conductivity model. Convergence is reached within a few iterations. The recovered model agrees well with the laterally averaged target model, although the latter comprises large jumps in conductivity. Our 1-D inversion scheme is therefore ready to process Swarm data.
Key words: Electromagnetic induction, 1-D inversion, mantle conductivity, C-responses.

Corresponding author E-mail: christoph.puethe@erdw.ethz.ch

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