Ultraviolet radiation as a proxy measurement for electrically generated hydroxyl radicals

Abstract

Reaction with hydroxyl radical (OH) initiates the removal of many pollutants from the atmosphere that impact human health and climate, but can also lead to the formation of different pollutants. Extreme amounts of OH are directly produced by lightning and other, weaker electrical discharges in the atmosphere, although estimates of the global impact of this source of OH are highly uncertain due to the limited field data. However, obtaining more field data is difficult, as measuring electrically generated OH with traditional OH-detecting instruments risks exposing both the instrument and the user to dangerous electrical currents. A possible alternative approach is to use the ultraviolet (UV) radiation generated by the electrical discharges as a proxy measurement for OH generation. Using a laboratory setup, the relationship between OH and UV radiation in different types of electrical discharges is investigated and quantified as a first step toward designing an instrument that can be safely deployed around electrical discharges in the field, leading to more certain estimates of the global impact of electrically generated OH.