Open AccessElectrical conductivity in the Earth's mantle inferred from CHAMP satellite measurements—I. Data processing and 1‐D inversion
Author(s) -
Velímský Jakub,
Martinec Zdeněk,
Everett Mark E.
Publication year - 2006
Publication title -
geophysical journal international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.302
H-Index - 168
eISSN - 1365-246X
pISSN - 0956-540X
DOI - 10.1111/j.1365-246x.2006.03013.x
Subject(s) - geophysics , geology , mantle (geology) , electrical resistivity and conductivity , conductivity , core–mantle boundary , inversion (geology) , electromagnetic induction , resistive touchscreen , electrical conductor , geodesy , seismology , physics , tectonics , electrical engineering , engineering , quantum mechanics , electromagnetic coil
SUMMARY A novel time‐domain approach to the global electromagnetic induction problem is applied to vector magnetometer data observed by the CHAMP satellite. Data recorded during 11 storm events in 2001–2003 are processed track by track, yielding time‐series of spherical harmonic coefficients. The data are then interpreted in terms of 1‐D layered electrical conductivity models. The inversion is performed by full search of model parametric space which yields sensitivity of misfit with respect to conductivities of layers and positions of interfaces. In the upper 50 km the inversion solidly recovers a conductive layer corresponding to averaged surface conductance. The conductivity of the lower mantle is established at 6 S m −1 assuming the upper–lower mantle interface is fixed at the seismic‐based 670 km boundary. However, the satellite data favour the models with a large jump around 1000 km to unrealistic conductivity values exceeding 10 3 S m −1 . The resolution of the method in the resistive upper mantle sandwiched between conductive crust and lower mantle is poor. Nevertheless, an upper bound of 0.01 S m −1 is suggested by the data. A conductivity increase in the transition zone is not observed.