Numerical Simulation of Electrical Space Charge Density and Lightning by using a 3-Dimensional Cloud-Resolving Model

Abstract

A new lightning formation scheme to simulate electrical space charge density and lightning is introduced into a 3-dimensional cloud-resolving model (JMANHM: Japan Meteorological Agency NonHydrostatic Model, Saito et al. 2006). A tripole structure in the electrical space charge distribution in cumulonimbi, clarified previous observational and numerical idealized studies (e.g., Williams 1989; Takahashi 1984), is well reproduced in numerical simulations with this new scheme.
The numerical simulations with the horizontal resolution of 1.5 km are performed to reproduce the thunderstorm observed over the Kanto area, the central part of the Japan Islands, on 08 July 2004. In these simulations, four electrical charge transfer methods are applied to this event. Among them, the modified method from Helsdon and Farley (1987) (mHF-method) predicts cloud-ground lightning polarity most successfully in comparison with the observations. The electrical space charge structures simulated with the mHF-method agree with the previous observational and idealized numerical studies.