Fig. 16From: Simultaneous inversion for source field and mantle electrical conductivity using the variable projection approachRecovered inducing field coefficient \(\varepsilon _{2}^1\) in the frequency domain. The frequency bands are the same as Fig. 5. In each subplot, we show the VP inversion results (thin cyan and pink lines) on top of the windowed spectra of the external field obtained by Gauss method (thick blue and red lines)Back to article page