Numerical tools for lightning return stroke current reconstruction by electromagnetic inverse problem formulation

An inverse problem is proposed for the identification of the lightning return stroke current, from the electro-magnetic fields that occur. The approach deals with Fredholm integral equations of the first kind and with an improved regularization procedure based on a spatial and time dependent harmonic reconstruction of the lightning current. All the preliminary evaluations appear to be in good agreement with the actual characterization models for return current of the lightning; moreover the precision as regarded to the effect is considerably improved.