(47b) The Lake Michigan Ozone Study (LMOS 2017) Field Campaign and Ozone Control Strategy from It

Spring and summertime ozone pollution remains a challenging air quality problem along the coast of Lake Michigan. Production of ozone over Lake Michigan combined with onshore daytime “lake breeze” airflow increases ozone concentrations preferentially at locations within a few kilometers of the shore. A collaborative field campaign (Lake Michigan Ozone Study 2017) took place during May and June 2017 to gather high spatio-temporal resolution data for refinement of conceptual thinking about these events, as well as evaluation and improvement of models. The campaign provided extensive observational datasets regarding ozone, its precursors, and the particulate matter and meteorology associated with ozone events through a combination of airborne, ship, mobile lab, and fixed ground-based sites.

The main observing systems during the campaign included GeoTASO, aircraft in situ ozone and NO₂ (Scientific Aviation), mobile lab trace gases (EPA region 5 GMAP), boundary layer profiling and column O₃, NO₂ and formaldehyde using a network of Pandora spectrometers and ceilometers, and on-lake sampling from the NOAA research vessel R5503. Two ground stations (Sheboygan WI and Zion IL) included meteorological vertical profiling, and in situ gas and aerosol sampling of a wide variety of aerosol, VOC, NO_y, and oVOC compounds.

An overview of the measurement platforms, meteorology, and air quality will be presented with a focus on sensitivities to emissions. The base case model had acceptable performance for daytime ozone overall (normalized mean bias of +1% domain-wide and -9% along the Lake Michigan coast), but failed to simulate many of the peak concentrations, due to a combination of meteorological and chemical errors. Sensitivities are explored using the photochemical grid model (PGM) WRF-Chem, including insights from tracking of individual reaction rates relevant to radical cycling and ozone production and the effects of perturbations of NO_x and total anthropogenic VOCs. Modeled NO₂ was over predicted during ozone episodes when compared with both ground sites and in situ flight data. Multiple lines of evidence (modeled sensitivity, modeled formaldehyde/NOx ratio, independent box modeling) indicate hydrocarbon limited conditions in the southern portion of the lake during some episodes. Sensitivity of ozone to anthropogenic hydrocarbon emissions was smaller in the northern portion of the lake. Back trajectory analysis indicated differing source regions for both ground sites, Sheboygan and Zion, one explanation for the observed result. Independent box modeling at the Zion IL site supports increases in anthropogenic hydrocarbon emissions. Analysis of further sensitivities to anthropogenic and biogenic VOCs will also be discussed.

References

Hughes, DD, Christiansen, M, Milani, A, Vermuel, MP, Novak, GA, Dickens, AF, Pierce, RB, Millet, DB, Bertram, TH, Stanier, CO, Stone, EA, Working Title: “Lake Michigan Ozone Study 2017: PM2.5 chemistry, organosulfates, and SOA formation”, Target: Atmos. Environ., In Preparation

Doak, A, Christiansen, M, Stanier, CO, Hughes, DD, Stone, EA, Millet, D, Alwe, H, Bertram, T, Working Title: “How Suitable Is Zion State Park as a Supersite for Understanding Lake Michigan Air Quality – A Site Characterization”, Target: JA&WMA, In Preparation

Vermeuel, M. P., Novak, G. A., Alwe, H. D., Hughes, D. D., Kaleel, R., Dickens, A. F., et al. ( 2019). Sensitivity of Ozone Production to NOx and VOC Along the Lake Michigan Coastline. Journal of Geophysical Research: Atmospheres, 124, 10989– 11006. https://doi.org/10.1029/2019JD030842

Abdi‐Oskouei, M., Carmichael, G., Christiansen, M., Ferrada, G., Roozitalab, B., Sobhani, N., et al. ( 2020). Sensitivity of meteorological skill to selection of WRF‐Chem physical parameterizations and impact on ozone prediction during the Lake Michigan Ozone Study (LMOS). Journal of Geophysical Research: Atmospheres, 125, e2019JD031971. https://doi.org/10.1029/2019JD031971