Electrically Generated Hydrogen Oxides in the Laboratory and Atmosphere
Open Access
- Author:
- Jenkins, Jena
- Graduate Program:
- Meteorology and Atmospheric Science
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- April 28, 2022
- Committee Members:
- Jerry Harrington, Major Field Member
William Brune, Chair & Dissertation Advisor
Victor Pasko, Outside Unit & Field Member
Kenneth Davis, Major Field Member
David Stensrud, Program Head/Chair - Keywords:
- hydroxyl radical
hydroperoxyl radical
ozone
nitrogen oxides
lightning
electrical discharges
corona discharges - Abstract:
- The hydroxyl radical is the most important oxidant in the troposphere, removing many pollutants, including greenhouse gases, but also generating new ones as it undergoes reactions. The hydroperoxyl radical is a product of these reactions and can be readily cycled back to hydroxyl when nitrogen oxides are present, so collectively hydroxyl and hydroperoxyl are called the hydrogen oxides (HOx). Electrical discharges have been known to generate prodigious amounts of the hydrogen oxides for decades, but were predicted to have lifetimes less than 10 ms, too short for lightning or corona discharges in the atmosphere to be a significant source of HOx. However, data from the Deep Convective Clouds and Chemistry field campaign in 2012 unexpectedly challenged this viewpoint. In this campaign, HOx was measured to be 100-1000 times higher specifically in the anvil clouds of thunderstorms, and subsequent work correlated some of the extreme HOx measurements to nearby lightning flashes. For this dissertation, a series of laboratory experiments were performed in order to determine whether electrical discharges in clouds caused this extreme HOx, and what environmental or electrical conditions may affect the production of this HOx. Sparks, corona, and subvisible discharges were all found to generate prodigious HOx. Additionally, HOx mixing ratios from spark discharges were found to have a longer-than-expected lifetime, and were mostly independent of pressures from 250-970 hPa, water vapor mixing ratios of 1000-8000 ppmv, and temperatures of -10 to 40°C. For subvisible discharges, HOx was also independent of temperature. For corona discharges on tree leaves, HOx production was strongly correlated with the ultraviolet flux of the discharge. These laboratory results of electrically generated HOx are shown to be relevant to the atmosphere through comparison with the DC3 results, and electrical discharges are a potentially significant source of HOx to the atmosphere.