Consideration of Shielding against Winter Lightning Based on Upward Leader Progression Model

Abstract

Many lightning stroke models of summer lightning have been proposed by various researchers up to this time. In Japan, it has been required to establish a new lightning shielding theory which considers upward leaders in winter lightning on the Japan Sea coast.
Differrences between lightning progression features of winter and summer lightnings prevent the conventional lightning stroke models of summer lightning from application to winter lightning.
Based on lightning observation data and discharge characteristics of long air gaps, a basic model of leader progression was previously proposed by the author. At this time, an improved model (upward leader progression model: ULP model), which considers statistical variation of leader progression, has been developed. This new model can reproduce various lightning features such as distribution of time-to-discharge, the ratio of numbers of lightning stroke to tall structures and so on.
Using the ULP model, shielding performances of high structures such as a lightning shielding tower and an overhead ground wire against winter lightning are predicted and compared with field observations.