Investigating Meteorological Influences on PM2.5 in Future Earth System Model Simulations with Superparameterized Convection

As the climate system adjusts to increases in the concentration of greenhouse gases, meteorological conditions are expected to change in ways that may influence the removal and transport of aerosol particles in the atmosphere. Precipitation, in particular, has a unique role in removing atmospheric pollutants by wet deposition. Though climate models project that the frequency of intense precipitation events will increase, the overall frequency of all precipitation events may decrease on a global-scale. Changes in precipitation frequency can impact aerosol removal processes in ways that may affect future air quality, even if aerosol emissions were to remain at present-day values. The study of these processes has been limited because global climate models can inaccurately represent the frequency and intensity of precipitation. However, these characteristics are improved when conventional convective parameterizations are replaced by high-resolution cloud resolving models (i.e., superparameterization). Using the Community Earth System Model (CESM) with conventional and superparameterization, we investigate how the representation of convection impacts the patterns of precipitation change, and therefore air quality under the CMIP6 SSP5-RCP8.5 21^st century scenario. In particular, changes in the surface concentration of fine particulate matter (PM2.5), which is hazardous to human health, are sensitive to cloud parameterization and changes in the character of precipitation. Additionally, the evolution of precipitation in the two versions of the model show changes that vary regionally, leading to regional hotspots of future air quality concern.