Evaluation of ozone and its precursors using the Multi-Scale Infrastructure for Chemistry and Aerosols Version 0 (MUSICAv0) during the Michigan–Ontario Ozone Source Experiment (MOOSE)

Le résumé fourni par la source

Surface ozone (O 3 ) in Southeast Michigan (SEMI) often exceeds US National Ambient Air Quality Standards, posing risks to human health and agroecosystems. SEMI, a relatively small region in the state of Michigan, contains most of the state's anthropogenic emission sources and more than half of the state's population and is also prone to long-range and transboundary pollutant transport. Here, we explore the distribution of O 3 and its precursors, such as nitrogen oxides (NO x ) and volatile organic compounds, over SEMI during the summer of 2021 using the chemistry–climate model MUSICAv0 (Multi-Scale Infrastructure for Chemistry and Aerosols Version 0). Using the regional refinement capabilities of MUSICAv0, we create a custom grid over the state of Michigan of 1/16° (∼ 7 km) to better understand the local-scale impacts of chemical and dynamic complexity in SEMI and compare it with a grid with 1/8° (∼ 14 km) resolution over the contiguous United States. Model simulations are evaluated using a comprehensive suite of observations from Phase I of the Michigan–Ontario Ozone Source Experiment (MOOSE) field campaign. MUSICAv0, with its higher horizontal grid resolution, showed excellent skill in capturing peak O 3 concentrations but showed larger variation in the simulation of O 3 precursors (e.g., NO x , HCHO, isoprene). In addition, we implement a diurnal cycle for anthropogenic nitric oxide (NO) emissions, which is generally not included in global models. As a result, modeled nighttime O 3 is improved because of lower NO x concentrations during the night. This work shows that when conceptualizing models in urban regions, it is important to consider a combination of high horizontal resolution and the diurnal cycle of emissions, as they can have important implications for the simulation of secondary air pollutants.

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