TITLE:
Transmission Line Modelling of Geomagnetic Induction in the Ocean/Earth Conductivity Structure
AUTHORS:
David H. Boteler, Shibaji Chakraborty, Xueling Shi, Michael D. Hartinger, Xuan Wang
KEYWORDS:
Geomagnetic Induction, Generalised Thin Sheet, Transmission Line Modelling, Coast Potentials, Submarine Cables
JOURNAL NAME:
International Journal of Geosciences,
Vol.14 No.8,
August
30,
2023
ABSTRACT: During geomagnetic disturbances, electric fields
induced in the Earth and in power systems, pipelines and submarine cables can
interfere with the operation of these systems. Calculations for submarine
cables are complicated by the need to consider not just the induction directly
into the cable but also the earth potentials produced at the coast at each end
of the cable. To determine the coast potentials, we present a new model of the
ocean and earth conductivity structure that
spans the whole length of a cable from one coast to another. Calculations are based on the generalised thin sheet approach introduced by
Ranganayaki and Madden but converted to a transmission line model that can be
solved using standard circuit theory techniques. It is shown how the
transmission line model can be used to calculate the earth potential profile
from one side of an ocean or sea to the other. Example calculations are
presented for a shallow sea, a shallow ocean, and a deep ocean that are
simplified approximations to the North Sea, Tasman Sea and Pacific Ocean and
show that the peak potentials occur at the coast. An examination is also made
of how the width of a shallow sea and the width of the continental shelf affect
these coast potentials. The modelling technique and example results provide a
guide for more detailed modelling of geomagnetic induction along the routes of
specific submarine cables.