Sensitivity of Ozone Production to NO_x and VOC Along the Lake Michigan Coastline

Abstract

We report on the sensitivity of enhanced ozone (O3) production, observed during lake breeze circulation along the coastline of Lake Michigan, to the concentrations of nitrogen oxides (NOx = NO + NO2) and volatile organic compounds (VOCs). We assess the sensitivity of O3 production to NOx and VOC on a high O3 day during the Lake Michigan Ozone Study 2017 using an observationally constrained chemical box model that implements the Master Chemical Mechanism (MCM v3.3.1) and recent emission inventories for NOx and VOCs. The Master Chemical Mechanism model is coupled to a backward air mass trajectory analysis from a ground supersite in Zion, IL, where an extensive series of measurements of O3 precursors and their oxidation products, including hydrogen peroxide (H2O2), nitric acid (HNO3), and particulate nitrates (NO3−) serve as model constraints. We evaluate the chemical evolution of the Chicago‐Gary urban plume as it advects over Lake Michigan and demonstrate how modeled indicators of VOC‐ versus NOx‐sensitive regimes can be constrained by measurements at the trajectory endpoint. Using the modeled ratio of the instantaneous H2O2 and HNO3 production rates (PH2O2/PHNO3), we suggest that O3 production over the urban source region is strongly VOC sensitive and progresses towards a more NOx‐sensitive regime as the plume advects north along the Lake Michigan coastline on this day. We also demonstrate that ground‐based measurements of the mean concentration ratio of H2O2 to HNO3 describe the sensitivity of O3 production to VOC and NOx as the integral of chemical production along the plume path.

Overview of the Lake Michigan Ozone Study 2017

“…We then present a high-level overview of the air quality and meteorological conditions observed during LMOS 2017, and discuss multi-model underprediction of peak ozone in both forecast and post-analysis configurations. We conclude with a summary of study findings to date and invitation for the community to access the LMOS (Judd et al, 2019;Vermeuel et al, 2019;Abdi-Oskouei et al, 2020;Doak et al, 2021;Hughes et al, 2021).…”

Simultaneous Detection of Ozone and Nitrogen Dioxide by Oxygen Anion Chemical Ionization Mass Spectrometry: A Fast Time Response Sensor Suitable for Eddy Covariance Measurements

“…Performance of the Ox-CIMS was compared against a co-located EPA Air Quality System (AQS) O3 monitor (Thermo-Fisher 49i, AQS ID 17-097-1007) over one month of ambient sampling during the Lake Michigan Ozone Study 2017 (LMOS 2017) in Zion, IL (Vermeuel et al, 2019). A regression analysis between the two instruments at one-minute averaging showed strong agreement (R = 0.99) as shown in Fig.…”

“…Oxygen anion (O ) reagent ion chemistry has been investigated previously for its use in the detection of nitric acid and more 115 recently hydrogen peroxide (Huey, 1996;O'Sullivan et al, 2018;Vermeuel et al, 2019). Oxygen anion chemistry has also been used for chemical analysis of aerosol particles in a thermal desorption instrument, primarily for detection of particle sulfate and nitrate (Voisin et al, 2003).…”

“…While the focus of this work is on detection of O3 and NO2, detection of hydrogen peroxide, nitric acid, formic acid, sulfur dioxide and other species with the Ox-CIMS has demonstrated good performance (Vermeuel et al, 2019). An example ambient mass spectrum recorded at 1 Hz sampling is shown in Fig.…”

“…Background of the Ox-CIMS was determined every 70 minutes by overflowing the inlet with dry UHP N2. Calibration factors for O3 were determined by scaling in-field continuous addition of a C-13 isotopically labelled formic acid standard to humidity dependent calibration factors for O3 and formic acid determined 340 in lab pre-and post-campaign as described in Vermeuel et al, (2019). The EPA O3 monitor shows a persistent high bias at low O3 concentrations (<10 ppbv) relative to the Ox-CIMS.…”