Grantee Research Project Results
2021 Progress Report: Development, validation and integration of a new model-ready parameterization of N2O5 heterogeneous chemistry.
EPA Grant Number: R840006Title: 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 July 31, 2023 (Extended to July 31, 2025)
Project Period Covered by this Report: August 1, 2020 through July 31,2021
Project Amount: $798,234
RFA: Chemical Mechanisms to Address New Challenges in Air Quality Modeling (2019) RFA Text | Recipients Lists
Research Category: Air , Air Quality and Air Toxics
Objective:
The primary objective of this proposal is development and validation of a new chemically based parameterization for ϒ(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 ϒ(N2O5) on aerosol composition and phase. We are currently implementing the revised Gaston et al. (2014) parameterization into CMAQ. In this implementation, the key variables for the ϒ(N2O5) parameterization are determined based on oxygen to carbon ratio (O:C) of the organic phase components in the particle and ambient relative humidity (RH). Using the values of O:C and RH, values for organic phase diffusion, reaction rate, and Henry’s law constant are determined. We have conducted full WINTER-period CMAQ simulations, covering 1 February 2015 through 16 March 2015, including 10 days of model spin- up. These simulations employ the following parameterizations: (1) default, (2) ϒ(N2O5) = 0, (3) ϒ(N2O5) = 0.03, (4) the Bertram and Thornton (2009) parameterization, (5) the Davis et al. (2008) parameterization. The sixth simulation, using the Gaston parameterization, is in progress.
Future Activities:
Our year 2 objectives center on evaluation of the model parameterizations developed for CMAQ. Specifically, we will calculate ϒ(N2O5) and Φ(ClNO2) along the flight track of the C-130 during the WINTER campaign (February 2015) and compare the model output with published aircraft determinations of ϒ(N2O5) and Φ(ClNO2). To meet these objectives, we will employ a regional modeling system: the EPA CMAQ model will be run at a 12 km × 12 km horizontal resolution and 35 vertical layers for the sampling region of the WINTER campaign (Eastern United States) February-March 2015.
References:
Bertram, T. H. and Thornton, J. A.: Toward a general parameterization of N2O5 reactivity on aqueous particles: the competing effects of particle liquid water, nitrate and chloride, Atmospheric Chemistry and Physics, 9, 8351–8363, https://doi.org/10.5194/acp-9-8351-2009, 2009.
Davis, J. M., Bhave, P. V., and Foley, K. M.: Parameterization of N2O5 reaction probabilities on the surface of particles containing ammonium, sulfate, and nitrate, Atmospheric Chemistry and Physics, 8, 5295–5311, https://doi.org/10.5194/acp-8-5295-2008, 2008.
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:
No journal articles submitted with this report: View all 1 publications for this projectSupplemental Keywords:
air quality, particulate nitrate, heterogeneous and multiphase chemistryRelevant Websites:
Bertram Research Group Exit and The Holloway Group Exit
Progress and Final Reports:
Original AbstractThe 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.