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Electrical conductivity of the Earth's mantle from the first Swarm magnetic field measurements
Author(s) -
Civet F.,
Thébault E.,
Verhoeven O.,
Langlais B.,
Saturnino D.
Publication year - 2015
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1002/2015gl063397
Subject(s) - mantle (geology) , geophysics , geology , lithosphere , electrical resistivity and conductivity , adiabatic process , earth's magnetic field , magnetotellurics , magnetic field , conductivity , physics , seismology , tectonics , thermodynamics , quantum mechanics
We present a 1‐D electrical conductivity profile of the Earth's mantle down to 2000 km derived from L1b Swarm satellite magnetic field measurements from November 2013 to September 2014. We first derive a model for the main magnetic field, correct the data for a lithospheric field model, and additionally select the data to reduce the contributions of the ionospheric field. We then model the primary and induced magnetospheric fields for periods between 2 and 256 days and perform a Bayesian inversion to obtain the probability density function for the electrical conductivity as function of depth. The conductivity increases by 3 orders of magnitude in the 400–900 km depth range. Assuming a pyrolitic mantle composition, this profile is interpreted in terms of temperature variations leading to a temperature gradient in the lower mantle that is close to adiabatic.