TY  - JOUR
AU  - von Hebel, Christian
AU  - van der Kruk, Jan
AU  - Huisman, Johan Alexander
AU  - Mester, Achim
AU  - Altdorff, Daniel
AU  - Endres, Anthony L.
AU  - Zimmermann, Egon
AU  - Garre, Sarah
AU  - Vereecken, Harry
TI  - Calibration, Conversion, and Quantitative Multi-Layer Inversion of Multi-Coil Rigid-Boom Electromagnetic Induction Data
JO  - Sensors
VL  - 19
IS  - 21
SN  - 1424-8220
CY  - Basel
PB  - MDPI
M1  - FZJ-2019-05329
SP  - 4753
PY  - 2019
AB  - Multi-coil electromagnetic induction (EMI) systems induce magnetic fields below and above the subsurface. The resulting magnetic field is measured at multiple coils increasingly separated from the transmitter in a rigid boom. This field relates to the subsurface apparent electrical conductivity (σa), and σa represents an average value for the depth range investigated with a specific coil separation and orientation. Multi-coil EMI data can be inverted to obtain layered bulk electrical conductivity models. However, above-ground stationary influences alter the signal and the inversion results can be unreliable. This study proposes an improved data processing chain, including EMI data calibration, conversion, and inversion. For the calibration of σa, three direct current resistivity techniques are compared: Electrical resistivity tomography with Dipole-Dipole and Schlumberger electrode arrays and vertical electrical soundings. All three methods obtained robust calibration results. The Dipole-Dipole-based calibration proved stable upon testing on different soil types. To further improve accuracy, we propose a non-linear exact EMI conversion to convert the magnetic field to σa. The complete processing workflow provides accurate and quantitative EMI data and the inversions reliable estimates of the intrinsic electrical conductivities. This improves the ability to combine EMI with, e.g., remote sensing, and the use of EMI for monitoring purposes.
LB  - PUB:(DE-HGF)16
C6  - pmid:31683890
UR  - <Go to ISI:>//WOS:000498834000150
DO  - DOI:10.3390/s19214753
UR  - https://juser.fz-juelich.de/record/866110
ER  -