Simplified Techniques for Treating the Ocean–Land Interface for Geomagnetically Induced Electric Fields

In this paper, two models for the calculation of geomagnetically induced electric fields near the shoreline are compared. The first is an analytic model which requires the solution of an integral equation at each frequency, and the second is a simplified model that only requires Fourier transforms. The mechanism responsible for the differing results is determined, and it is suggested that one of the features of the analytic model should be included in the simplified model. This modification can be made without reducing the computational advantages of the second model. We also show the relative effect of the shoreline enhancement on the voltage impressed on cables for two different ground conductivities.