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A study on the influence of corona on currents and electromagnetic fields predicted by a nonlinear lightning return‐stroke model
Author(s) -
De Conti Alberto,
Silveira Fernando H.,
Visacro Silvério
Publication year - 2014
Publication title -
journal of geophysical research: atmospheres
Language(s) - English
Resource type - Journals
eISSN - 2169-8996
pISSN - 2169-897X
DOI - 10.1002/2013jd020915
Subject(s) - electric field , lightning (connector) , physics , mechanics , amplitude , corona (planetary geology) , electromagnetic field , transmission line , nonlinear system , computational physics , waveform , acoustics , electrical engineering , engineering , voltage , optics , power (physics) , quantum mechanics , astrobiology , venus
This paper investigates the influence of corona on currents and electromagnetic fields predicted by a return‐stroke model that represents the lightning channel as a nonuniform transmission line with time‐varying (nonlinear) resistance. The corona model used in this paper allows the calculation of corona currents as a function of the radial electric field in the vicinity of the channel. A parametric study is presented to investigate the influence of corona parameters, such as the breakdown electric field and the critical electric field for the stable propagation of streamers, on predicted currents and electromagnetic fields. The results show that, regardless of the assumed corona parameters, the incorporation of corona into the nonuniform and nonlinear transmission line model under investigation modifies the model predictions so that they consistently reproduce most of the typical features of experimentally observed lightning electromagnetic fields and return‐stroke speed profiles. In particular, it is shown that the proposed model leads to close vertical electric fields presenting waveforms, amplitudes, and decay with distance in good agreement with dart leader electric field changes measured in triggered lightning experiments. A comparison with popular engineering return‐stroke models further confirms the model's ability to predict consistent electric field waveforms in the close vicinity of the channel. Some differences observed in the field amplitudes calculated with the different models can be related to the fact that current distortion, while present in the proposed model, is ultimately neglected in the considered engineering return‐stroke models.