Date of Award

1-1-2020

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

College/School/Department

Department of Atmospheric and Environmental Sciences

Content Description

1 online resource (xxx, 193 pages) : color illustrations, color maps.

Dissertation/Thesis Chair

James Schwab

Committee Members

Sarah Lu, Xianliang Zhou, Robert Keesee

Keywords

Nitrogen oxides, Ozone, Ozone production efficiency, Re-noxification, Reactive oxidized nitrogen, Atmospheric nitrogen oxides, Atmospheric chemistry, Air quality management, Nitrogen Oxides

Subject Categories

Atmospheric Sciences | Other Chemistry

Abstract

Ongoing reductions in oxides of nitrogen concentrations ([NOx] = nitric oxide ([NO]) + nitrogen dioxide ([NO2])) throughout the continental United States (U.S.) have important implications for tropospheric ozone (O3) and reactive oxidized nitrogen chemistry (NOy ≈ NOx + nitric acid (HNO3) + particle nitrate (pNO3) + peroxy nitrates (PNs) + alkyl nitrates (ANs)). Specifically, decreasing [NOx] concentrations have likely (1) increased the sensitivity of O3 to the [NOx] level, and (2) affected NOy speciation and partitioning. An understanding of the impacts of continued [NOx] reductions is needed to inform current and future air pollution control strategies, especially since the National Ambient Air Quality Standard (NAAQS) for O3 was lowered from 75 to 70 parts per billion (ppb) in 2015. The lower O3 NAAQS has made it more difficult for areas downwind of urban areas characterized by complex emissions (e.g., New York City) to be in O3 attainment.

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