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Emission sensitivity (O3 / NOx / VOC) Lake Michigan - at JGR Atmospheres

Updated: Nov 23, 2022

with model outputs archived Iowa Research Online in observance of the JGR data and transparency polices: doi: 10.25820/data.006193 (

BONUS QUESTION: What time of day will FNR from satellites have the most information for management of high ozone days! (scroll down for the answer)

Thanks to the whole LMOS crew!

TITLE: The Impact of Volatile Chemical Products, Other VOCs, and NOx on Peak Ozone in 1 the Lake Michigan Region

Maryam Abdi-Oskouei, Behrooz Roozitalab, Charles O. Stanier, Megan Christiansen, Gabriele Pfister, R. Bradley Pierce, Brian C. McDonald, Zac Adelman, Mark Janssen, Angela F. Dickens, and Gregory R. Carmichael

Radical (OH, HO2, RO2) loss processes on high ozone days. Radicals important for ozone formation are lost via reactions with NOx (warm colors) and with RO2 radicals (cool colors) with implications for air quality management.

ABSTRACT: High concentrations of ozone along the coastline of Lake Michigan are a persistent air quality management challenge. Complementing observations during the 2017 Lake Michigan Ozone Study (LMOS 2017), WRF-Chem modeling was used to quantify sensitivity of modeled ozone (O3) to anthropogenic nitrogen oxides (NOx) and Volatile Organic Compound (VOC) emissions, including to changes in Volatile Chemical Products (VCP). The daily maximum 8 h average (MDA8) over the high ozone region of Lake Michigan decreased by 2.7 ppb with exclusion of VCP from the inventory, and was sensitive to both NOx and VOC changes, with greater sensitivity to NOx. Close to urban centers, MDA8 ozone was VOC-sensitive. Clusters of coastal receptor sites were identified based on similarity in response to emission perturbations, with most clusters being NOx-sensitive and NOx sensitivity increasing with distance from major emission sources. The June 2, 2017 ozone event, which has received considerable focus, is shown to be atypical due to unusually strong and spatially extended VOC-sensitive behavior. WRF-Chem Integrated Reaction Rate (IRR) analysis was used to compute radical termination rates due to NOx (LNOx) and to radical-radical reactions (LROx). LROx/LNOx and formaldehyde to NO2 ratio (FNR) were shown to be predictive of modeled MDA8 ozone sensitivity, but with variation in predictive power as a function of time of day, which has implications for air quality management use of FNR from geostationary satellites.

During LMOS 2017, boundary layer Formaldehyde to NO2 ratio (FNR) was somewhat predictive of emission sensitivity on high ozone days (blue curve), and it was most predictive at 12 noon.



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