ROCKET-TRIGGERED LIGHTNING: MODELING OF TRIGGER-WlRE CORONA EFFECTS

For the first time, a model gives due consideration to the effect of space charge produced by trigger-wire glow-corona on continuous upward leader onset, in rocket triggered lightning under negative cloud. The model includes the effects space charge from bush corona resulting in non-uniformity of the ambient field into which the rocket is launched, as well as the effects of rocket speed and ambient relative air density. The paper shows that the effect of trigger-wire glow-corona on continuous upward leader onset is quite substantial, emphasizing the basic difference in this respect between tall static structures and rocket-triggered lightning. The work confirms the importance of two necessary and sufficient criteria for continuous upward leader onset, a global criterion relating to the space potential at the wire-tip height and a local criterion regarding the ambient field aloft. The model has been applied to several previous field experiments characterized by a wide variety of rocket speeds, bush coronas and ambient relative air densities. Comparison between model and experimental results, including the more recent and better instrumented, was found very satisfactory.