Based on Kutateladze's fictitious layer method (or additional wall method), a non-isothermal earth surface can be modelled with the help of a fictitious earth layer with thickness $d_{im}$. The cable image line source is then placed at distance $L_{cni}$ above the fictitious layer.

The method is based on a paper from 2014 by Sujit Purushothaman.

Symbol
$L_{\mathrm{cni}}$
Unit
m
Formulae
$L_{\mathrm{cm}} + d_{\mathrm{im}}$
Related
$d_{\mathrm{im}}$
$L_{\mathrm{cm}}$