Modeling the effect of the ocean-land interface on induced electric fields during geomagnetic storms

[1] In this paper a model is developed for the calculation of the enhancement of geomagnetic storm electric fields near ocean-land interfaces. The motivation for this work is the calculation of the electric fields applied to power and telecommunication conductors near the seashore. This model consists of an ocean of depth linearly increasing with distance from the shoreline and a uniformly conducting soil. With this assumption an integral equation is obtained for the electric field for exponentially rising surface magnetic fields. This equation is solved numerically and, for a special limiting case, analytically. Solutions for two different surface magnetic field time histories at the surface are obtained by taking inverse Laplace transforms. Expressions are derived for the change in the electric field when compared with the electric field at the surface of a homogeneous Earth. Numerical examples are given for the enhancement of the electric field for sudden storm commencement and electrojet magnetic field time histories.