This project is focused on improving measurement methods for hydroxyl and hydroperoxyl radicals (OH and HO2) in the atmosphere. These compounds are very reactive and known to ?cleanse? the atmosphere by oxidizing and breaking down a number of trace species and pollutants so that they are removed from the atmosphere. Understanding atmospheric oxidation chemistry is critical for establishing the links between atmospheric composition, air quality, and climate change.
One method for measuring OH and HO2 is the Fluorescence Assay by Gas Expansion (FAGE) instrument using a Ground-based Tropospheric Hydrogen Oxides Sensor (GTHOS). In the past, there have been discrepancies between the GTHOS/FAGE measured values and the modeled values of OH and HO2, primarily showing greater-than-expected OH in low-nitrogen oxides (NOx) environments and greater-than-expected HO2 in high-NOx environments.
The proposed effort consists of three main tasks: (1) identifying the cause of the OH interference in the measurement instrument (GTHOS/FAGE) and implementing instrument changes to minimize its impact on OH measurement; (2) resolving the issues of HOx-NOx chemistry with focused laboratory studies; and (3) lowering the GTHOS limit-of-detection to 105 OH cm-3 and the absolute uncertainty to 20% (95% confidence).
This proposal has a high potential to transform current understanding of atmospheric chemistry, including air pollution chemistry and the forcing of global climate by radiatively active species that respond to changes in this chemistry.
|Effective start/end date||4/15/15 → 3/31/19|
- National Science Foundation: $379,727.00