Grantee Research Project Results

2022 Progress Report: Development, validation and integration of a new model-ready parameterization of N2O5 heterogeneous chemistry.

EPA Grant Number: R840006
Title: Development, validation and integration of a new model-ready parameterization of N2O5 heterogeneous chemistry.
Investigators: Bertram, Timothy , Holloway, Tracey
Institution: University of Wisconsin - Madison
EPA Project Officer: Chung, Serena
Project Period: August 1, 2020 through May 8, 2025
Project Period Covered by this Report: August 1, 2021 through July 31,2022
Project Amount: $798,234
RFA: Chemical Mechanisms to Address New Challenges in Air Quality Modeling (2019) RFA Text | Recipients Lists
Research Category: Watersheds , Endocrine Disruptors , Environmental Engineering , Air Quality and Air Toxics , Air

Objective:

The primary objective of this proposal is development and validation of a new chemically based parameterization for γ(N₂O₅) and Φ(ClNO₂) that accounts for recent insights from laboratory and field measurements of N₂O₅ and ClNO₂ heterogeneous chemistry, with a specific focus on the role of phase separation and aerosol water in regulating reactive uptake of N₂O₅. The chemically based parameterization will be constructed such that they can be readily integrated into CMAQv5.3 leveraging new advances in organic aerosol treatment in the model.

Progress Summary:

During year one, we focused on the testing and implementation of a modified version of the Gaston et al. (2014) N₂O₅ parameterization to account for the dependencies of γ(N₂O₅) on aerosol composition and phase. In year two, we focus on ClNO₂ chemistry. Four combinations of Φ(ClNO₂) and γ(N₂O₅) parameterizations were tested within CMAQ. These four combinations were compared with flight data for Φ(ClNO₂) and γ(N₂O₅) from the WINTER 2015 campaign. More specifically, we implemented a new parameterization for ClNO₂ production based on recent laboratory and field measurements that suggest that sulfate can act to catalyze the hydrolysis of N₂O₅, thus reducing the ClNO₂ yield. However, when testing these parameterizations, our initial results suggest that the two parameterizations are quite similar. Specifically, at a 95% confidence, a comparison of the two Φ(ClNO₂) parameterizations failed to reject the null hypothesis (𝐷=0.01,𝑝=0.997) indicating that the two model parameterization combinations were not statistically different. We are currently extracting N₂O₅ and ClNO₂ concentrations along the flight track of the WINTER campaign for comparison with CMAQ.

Future Activities:

Our year 3 objectives center on assessing CMAQ representations of γ(N₂O₅) and Φ(ClNO₂) using early morning tropospheric column NO₂ measurements from Pandora (ground-based) and TEMPO (future satellite) and assess the response of model O₃ and PM to updated nocturnal NOx chemistry.

References:

Gaston, C. J., Thornton, J. A., and Ng, N. L. Reactive uptake of N₂O₅ to internally mixed inorganic and organic particles: the role of organic carbon oxidation state and inferred organic phase separations, Atmospheric Chemistry and Physics, 14, 5693–5707, https://doi.org/10.5194/acp-14-5693-2014, 2014.

Journal Articles on this Report : 1 Displayed | Download in RIS Format

Publications Views
Other project views:	All 2 publications	2 publications in selected types	All 2 journal articles

Publications
Type	Citation	Project	Document Sources
Journal Article	Bergin RA, Harkey M, Hoffman A, Moore RH, Anderson B, Beyersdorf A, Ziemba L, Thornhill L, Winstead E, Holloway T, Bertram TH. Observation-based constraints on modeled aerosol surface area:implications for heterogeneous chemistry. Atmospheric Chemistry and Physics 2022;22:15449–68.	R840006 (2022) R840006 (2023) R840006 (2024)	Full-text: Copernicus - Full Text HTML Exit

Supplemental Keywords:

air quality, particulate nitrate, heterogeneous and multiphase chemistry

Relevant Websites:

The Holloway Group at SAGE Exit , The Bertram Research Group Exit

Progress and Final Reports:

Original Abstract

The perspectives, information and conclusions conveyed in research project abstracts, progress reports, final reports, journal abstracts and journal publications convey the viewpoints of the principal investigator and may not represent the views and policies of ORD and EPA. Conclusions drawn by the principal investigators have not been reviewed by the Agency.