Examining the Influence of Meteorology on High O3 and PM2.5 Events at Chiwaukee Prairie in June 2022

Air quality has a direct impact on human health, such as respiratory illnesses and shortness of breath. In June 2022, Chiwaukee Prairie, WI, experienced poor air quality due to abnormally high amounts of ozone (O3) and fine particulate matter (PM2.5). Chiwaukee Prairie is located north of Chicago, IL, along the Lake Michigan shoreline. The combination of Chicago’s heavily populated city with high emissions and transport associated with Lake Michigan’s lake breeze often makes O3 and PM2.5 levels high at Chiwaukee Prairie. This study was done to understand the relationship between meteorology, on a synoptic scale and mesoscale, and the elevated amounts of O3 and PM2.5 on June 14, 2022, and June 15, 2022, respectively. To do so, we used data from the Wisconsin Department of Natural Resources Enhanced Ozone Monitoring (EOM) program, the North American Regional Reanalysis (NARR), and the Geostationary Operational Environmental Satellite Program (GOES-16). The EOM dataset gave us insight into the nature of mesoscale meteorology and chemistry in the area. The variables we used from the EOM dataset were O3, PM2.5, wind direction, wind speed, temperature, and nitrogen dioxide (NO2). We then created time series plots of meteorological variables compared to O3 and PM2.5 to understand their relationship. This data, specifically wind speed, wind direction, and temperature showed clear evidence of a lake breeze that impacted ozone levels. With the data from NARR, we made hourly composites at 0z, 6z, 12z, and 18z that displayed geopotential height and wind vectors at 850mb. We then looked at satellite data from GOES-16 to see the cloud behavior on specific days. We were able to understand the synoptic meteorology taking place on high-pollution days by looking at how these components changed at different times. We found that the high O3 event was driven by a lake breeze circulation, while the high PM2.5 event was driven by synoptic-scale flow. Future directions of study include examining volatile organic compounds (VOCs) and their relationship to ozone, as well as comparing other high-level O3 and PM2.5 days to what was found in June 2022.