Investigation of lightning ignition characteristics based on an impulse current generator

Abstract

Lightning strike is an important ignition source of forest fires. Artificial lightning discharge is a method for studying lightning fires. However, there is not enough data on the ignition of combustible materials caused by artificial lightning discharge. Previous studies on lightning ignition have focused on the heating and ignition effects of long continuing current (LCC), but the function of the impulse current that occurs before the LCC has not been taken into account. In this paper, an impulse current generator of 8/20 μs was used to simulate the ignition effect of impulse current on conifer needle beds. Different current waveforms have different ignition characteristics. We compared five kinds of conifer needle beds. The average of the current needed to ignite the needle bed of Larix gmelinii (Ruprecht) Kuzeneva was the smallest, and the average of the breakdown voltage was the smallest for the needle bed of Pinus massoniana Lamb. The total energy input to the conifer needle beds was fitted as a multiple log‐linear regression model. The heating energy proportion value varies with different bulk densities, current amplitudes, and moisture contents. Based on this data, the heating energy of the impulse current transferred to the needles can be predicted. This information in conjunction with previous research on LCC was used to derive a lightning ignition prediction model of the full waveform for conifer needle beds.

A parameterization of Long-Continuing-Current (LCC) lightning in the lightning submodel LNOX (version 3.0) of the Modular Earth Submodel System (MESSy, version 2.54)

“…LCC-lightning has been associated with lightning-ignited fires (e.g., Fuquay et al, 1967;Latham and Williams, 2001;Pineda et al, 2014;Pérez-Invernón et al, 2021b), as the long duration of the discharge can favor ignition. This assumption is supported by laboratory experiments (e.g., McEachron and Hagenguth, 1942;Feng et al, 2019;Zhang et al, 2021). LCClightning is also proposed to be the main precursor of sprites (Bell et al, 1998;Cummer and Füllekrug, 2001;Cummer, 2003), a type of Transient Luminous Event (TLE) taking place in the mesosphere above thunderclouds (Pasko et al, 2012;Gordillo-Vázquez and Pérez-Invernón, 2021).…”

On the Role of Continuing Currents in Lightning‐Induced Fire Ignition

“…The role of continuing currents in LIW was previously suggested by field and laboratory observations (Feng et al, 2019;McEachron & Hagenguth, 1942;H. Zhang et al, 2021).…”

“…For this reason, lightning flashes with CC have been proposed to be the main precursors of lightning ignitions (Anderson, 2002, an references therein). This hypothesis is supported by multiple laboratory experiments (e.g., Feng et al., 2019; McEachron & Hagenguth, 1942; H. Zhang et al., 2021) and some field and satellite‐based observations (e.g., D. M. Fuquay et al., 1967; D. Fuquay et al., 1972; Latham & Williams, 2001; Pérez‐Invernón et al., 2021, 2023). However, the characteristics of the electromagnetic signals produced by continuing currents prevent a continuous monitoring of their occurrence by using ground‐based lightning location systems, making it difficult to quantify the number of wildfires caused by CC.…”

Variation of lightning-ignited wildfire patterns under climate change

“…The occurrence of lightning-ignited wildfires, in turn, is related to the meteorological conditions that favor the occurrence of lightning and fuel availability. Multiple laboratory experiments [e. g., [2][3][4]] and field observations [e. g., [5][6][7]] indicate that continuing electrical currents in lightning flowing for more than tens of milli-seconds (socalled Long-Continuing-Currents, LCC) are likely to produce fires. The evolution and spreading of fires are determined by fuel availability and meteorological conditions, such as air temperature, precipitation rate, and wind strength [8][9][10][11][12][13][14].…”