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Abstract Reaction with the hydroxyl radical (OH) is often the first step in the removal of many atmospheric pollutants. The nitrogen oxides (NOx) generated by lightning can increase the amount of HOx(HOx = OH + HO2) present in the atmosphere, but direct HOxproduction from lightning has never been quantitatively investigated in the laboratory. In this laboratory study, prodigious amounts of HOxwere generated by both visible and subvisible electrical discharges over ranges of pressure and water vapor mixing ratios relevant to the troposphere. Also measured were NO, total nitrogen oxides (NOx), ozone (O3), and OH exposure, which is the integral of the hydroxyl radical concentration over time since the discharge. HOxand OH exposure were approximately independent of pressure from 360 to 970 hPa and increased only slightly as water vapor increased from 1,000 to 8,000 parts per million volume (ppmv), while NOxwas approximately independent of both pressure and water vapor over the same ranges. These laboratory measurements of excessive HOxand OH exposure are similar to measurements of electrically generated HOxdiscovered in electrified anvil clouds during a 2012 airborne study, thus demonstrating the relevance of these laboratory results to the atmosphere and the importance of understanding the electrically generated HOxcontribution to atmospheric oxidation.
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Prodigious Amounts of Hydrogen Oxides Generated by Corona Discharges on Tree Leaves
Abstract Prodigious amounts of the hydroxyl radical (OH) are generated in the laboratory on tree leaves by corona discharges, which also occur on trees during thunderstorms. Production rates of OH and HO2depend on the applied electric field generating the corona discharge, leaf dryness, and the presence of liquid water on the leaf. However, they are independent of leaf type and corona discharge polarity for a given corona ultraviolet (UV) flux. Production rates of OH, HO2, and O3strongly correlate with corona UV flux. Although the contribution of corona‐produced OH to total global OH production is unlikely to be important, corona‐generated OH is likely a few orders of magnitude greater than oxidation by known processes in the vicinity of the affected leaves, potentially influencing atmospheric oxidation and tree and forest ecology.
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- Award ID(s):
- 1834711
- PAR ID:
- 10371958
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 127
- Issue:
- 16
- ISSN:
- 2169-897X
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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