On the Importance of Considering Realistic Orography Into the Evaluation of Lightning Electromagnetic Fields in Mixed Path

A lightning event striking the sea could induce several damages to the near infrastructures located on the coast. The possible damages are connected to the induced voltages caused by the electromagnetic fields generated by the lightning discharge. In order to compute them, several simplified approaches have been developed, using ideal models for the surrounding geometry and for the electrical parameters of the soil. This works provides the evaluation of the lightning electromagnetic fields generated by a lightning event striking on the sea taking into account the possible elevation of the terrain with respect to the sea level and the inclination of the seabed. The analysis has been carried out taking into account several distances between the coast and the striking location as well as different observation points, in order to evaluate the induced effects on a structure located close to the sea–land interface as well as in a more distant location. The analysis, implemented with the aid of the finite element method, leads to important conclusions on the components of the electric and magnetic field that are more affected by the realistic characteristics of the surrounding orography.