Influence of Space Charge on Upward Leader Initiation

Abstract

Upward lightning is often observed on the coast of the Sea of Japan in winter season. Space charges by corona discharges at the grounded structures and on the ground or from the sea surface greatly affect the upward leader initiation, however, no studies of the effect of space charges have been carried out yet. In this paper, we calculate the electric fields around a conductor considering the effect of corona discharge from the conductor itself and on the ground using the DC ion flow calculation program that was developed by CRIEPI. Calculation results show that the upward leader initiation criteria are difficult to be satisfied for small conductors than large conductors because space charge reduces the electric field for the small conductors, and that space charge from conductors gives remarkable effects including polarity change on the ground level electric field in the downwind area.