P. Schmoldt, PhD - MTNet - DIAS

A. Appendix
A.2. Auxiliary information regarding inversion
processes
A.2.1. Creating the inversion mesh
This Section explains the general procedure of creating the mesh used for 2D inversion
(slight alterations are conducted between inversions). Initially a default mesh without
topography is created using the user defined mesh tool of the WinGLink inversion
software package [WinGLink, 2005]; therein the following parameters are applied:
• Mesh resistivity value: 1000 Ωm,
• increase factor for the horizontal block width: 1.2,
• target width for station column: 1.2 of a skin depth,
• increase factor for the vertical block width: 1.1.
Thereafter, additional columns are added along some parts of the profile to facilitate a
minimum of two columns between each pair of stations throughout the entire mesh in
order to allow compensation of topographic effects not accounted for with the plane model
used herein (cf. Section 4 for a discussion of topographic distortion effects). Subsequently
mesh values are changed to 100 Ωm (or respective values for the layered model case). In a
final step all cells below a depth of approximately ten times the skin depth (see Eq. 3.44)
for the longest period are removed to reduce mesh size and, thereby, computationally
costs (cf. Sec. 6.3). Moreover, a conductivity of 1 Ωm is assigned to cells in the bottom
row to ensure that boundary conditions are met.
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