Lightning Electromagnetic Field Calculation Using the Constrained Interpolation Profile Method With a Subgridding Technique

The constrained interpolation profile (CIP) method has been recently applied to analyzing lightning electromagnetic fields. This method has an advantage that it is capable of computing electromagnetic fields reasonably accurately even when a relatively coarse grid is used. However, in analyzing small structures (in comparison with grid size) in the field point, this advantage of the CIP method is no longer valid and a locally fine grid would need to be employed. In this letter, a subgridding technique is applied to analyzing lightning electromagnetic fields in the three-dimensional space with the CIP method.