Grantee Research Project Results

Modeling the Effect of CINO2 on Downwind Transport of NOx During Winter

EPA Grant Number: FP917785
Title: Modeling the Effect of CINO2 on Downwind Transport of NOx During Winter
Investigators: Haskins, Jessica Danielle
Institution: University of Washington
EPA Project Officer: Lee, Sonja
Project Period: September 1, 2015 through August 31, 2018
Project Amount: $88,000
RFA: STAR Graduate Fellowships (2015) RFA Text |  Recipients Lists
Research Category: Academic Fellowships

Objective:

The first objective of this research is to observationally constrain the uptake coefficient of N2O5 and the yield of ClNO2 and identify or develop a best parameterization for their improved implementation in GEOS-Chem. The second is to use the resulting model to address the research questions: What is the role of ClNO2 on the speciation of NOy and the distribution of reactive nitrogens over the eastern U.S.? How has this chemistry impacted the seasonal air quality (i.e. ozone chemistry, VOC oxidation, nitrate aerosol formation) over the eastern US?

Approach:

I will use the Wintertime INvestigation of Transport, Emissions, and Reactivity 2015 (WINTER) campaign measurements and known literature values to define chemical and physical parameters such as reaction probabilities, product yields, uptake rates, and deposition velocities within GEOS-Chem. After determining the numeric values needed for these parameters, I will implement full tropospheric chlorine chemistry into GEOS-Chem. The resulting model predictions of nitrogen oxides, ozone, and particulate nitrate will be compared to WINTER aircraft observations, the National Emissions Inventory database, and the EPA’s Air Quality System to determine how well the new chemistry explains existing observations of these pollutants. Then, the model will be run to analyze the results of changing emissions on seasonal air quality around the globe.

Expected Results:

GEOS-Chem is known to represent ozone, a major component in smog, particularly badly during winter. We expect that including ClNO2 chemistry will improve the model’s ability to predict wintertime ozone concentrations. Preliminary comparisons between GEOS-Chem and WINTER observations show a factor of 2-4 overestimate in particulate nitrate, which has been noted in previous, independent studies. We expect that allowing ClNO2 formation within GEOS-Chem will reduce this bias. It has been shown that during observed elevated particulate matter (PM) episodes in the Midwestern U.S., particulate nitrate was the driving anthropogenic component of the wintertime exceedences. This project hopes to better represent GEOS-Chem’s ability to predict and explain such bad air quality events in the future.

Supplemental Keywords:

Reactive nitrogen, yield ClNO2, gamma N2O5, wintertime ozone production, GEOS-Chem

Progress and Final Reports:

2016

2017

Final