Estimation of Lightning Stroke Peak Current as a Function of Peak Electric Field and the Normalized Amplitude of Signal Strength: Corrections and Improvements

Abstract

The authors have made connections and improvements to published equations relating the peak current and the peak electric field intensity for return strokes of cloud-to-ground lightning. The original published equations were derived from measurements of rocket-wire-triggered lightning made at the Rocket-Triggered-Lightning Program (RTLP) Facility at the Kennedy Space Center in Florida. Previous articles published by others included errors in the conversion of the equations from volts per meter (for peak electric field), to a proportional quantity, LLP (lightning location and protection units), representing range-normalized signal strength amplitude. The proper conversion procedure and the resultant corrected equations are presented in this paper. Also presented are equations produced by converting other published relationships. The authors combined rocket-triggered-lightning data for 1985?91 from the RTLP facility to produce a regression equation of peak current and range-normalized signal strength amplitude (in LLP units) based on a larger dataset than previous investigators used. The resulting equation supports the conclusion from theoretical work that the peak current varies with range-normalized signal strength amplitude to give a slope of 0.2 for a zero intercept. Most of the regression equations in the text are tabulated; three are compared graphically.