Measuring NOx and O3 emissions from laboratory generated lightning

Lightning flashes are a major source of tropospheric NO_x, which leads to the production of tropospheric O₃ (Elshorbany et al., 2024). Tropospheric O₃ is an important greenhouse gas (Skeie et al., 2020), and lightning rates are predicted to increase with global warming (e.g., Pinto & Pinto, 2020; Romps et al., 2014), creating a positive feedback loop. Laboratory-based measurements are a means to improve the parameterisation of this source to improve the accuracy of climate models. 

We sampled concentrations of NO, NO₂ and O₃ produced following lightning generated at Cardiff University’s Lightning Laboratory, the only university-based research laboratory of its type in Europe. The laboratory generated D waveforms (peak currents ranging from 10 to 100 kA over 100 µs) and C waveforms (~250 A for 0.5 s) conforming to the EUROCAE ED-84 and its SAE equivalent standards. The D waveform represents the initial impulse and any subsequent restrikes, whereas the C represents the long-duration continuing current seen in ~10% of lightning waveforms (Pérez-Invernón et al., 2023). An array of low-cost sensors recorded gas concentrations following strikes. Despite some disruption due to the lightning Electro-Magnetic Pulse (EMP), and instances where high concentrations have saturated the sensors, initial results demonstrate the feasibility of measuring lightning NO_X and O₃ generation in the laboratory. This provides a foundation for future developments with a view to better quantifying the impact of lightning strikes on tropospheric chemistry and investigating how this varies with the waveform and power dissipated by the strike. 

 

References 

Elshorbany, Yasin, et al. “Tropospheric Ozone Precursors: Global and Regional Distributions, Trends, and Variability.” Atmospheric Chemistry and Physics, vol. 24, no. 21, 5 Nov. 2024, pp. 12225–12257, acp.copernicus.org/articles/24/12225/2024/?form=MG0AV3, https://doi.org/10.5194/acp-24-12225-2024. 

J., Osmar Pinto, and Iara R. C. A. Pinto. “Lightning Changes in Response to Global Warming in Rio de Janeiro, Brazil.” American Journal of Climate Change, vol. 09, no. 03, 2020, pp. 266–273, https://doi.org/10.4236/ajcc.2020.93017. 

Pérez-Invernón, Francisco J., et al. “Variation of Lightning-Ignited Wildfire Patterns under Climate Change.” Nature Communications, vol. 14, no. 1, 10 Feb. 2023, https://doi.org/10.1038/s41467-023-36500-5. 

Romps, D. M., et al. “Projected Increase in Lightning Strikes in the United States due to Global Warming.” Science, vol. 346, no. 6211, 13 Nov. 2014, pp. 851–854, science.sciencemag.org/content/346/6211/851, https://doi.org/10.1126/science.1259100. 

Skeie, Ragnhild Bieltvedt, et al. “Historical Total Ozone Radiative Forcing Derived from CMIP6 Simulations.” Npj Climate and Atmospheric Science, vol. 3, no. 1, 17 Aug. 2020, https://doi.org/10.1038/s41612-020-00131-0.