Geophysical Research Letters

Strong sensitivity of the global mean OH concentration and the tropospheric oxidizing efficiency to the source of NOx from lightning

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Abstract

[1] Production of nitrogen oxides (NOx = NO + NO2) by lightning (LtNOx) is the most uncertain among the global NOx sources, with recent estimates ranging from about 1–20 Tg(N)/yr. Previous studies of LtNOx have focused mainly on its role in the tropospheric NOy (reactive nitrogen) and O3 budgets. We show that the global mean OH concentration is also very sensitive to LtNOx. Furthermore, despite the fact that the largest changes in NOx due to lightning are in the upper troposphere, where reactions with OH are generally slower, we find that the sensitivity of the mean tropospheric lifetime of methane (CH4) and methylchloroform (CH3CCl3) to assumptions about LtNOx are as large as the sensitivity of the tropospheric O3 burden. Thus, an improved understanding of LtNOx will be important for our ability to accurately simulate the tropospheric oxidizing efficiency and its changes over time.

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