Capturing High-Resolution Air Pollution Features Using the Multi-Scale Infrastructure for Chemistry and Aerosols Version 0 (MUSCIAv0) Global Modeling System

The Multi-Scale Infrastructure for Chemistry and Aerosols (MUSICA) enables the study of atmospheric chemistry and aerosols at global to local scales. MUSICA version 0 (MUSICAv0) is a configuration of the Community Earth System Model (CESM) with regional refinement (RR). We compared the regional scale spatial and temporal variabilities of air pollutants simulated by this newly developed multiscale model and a widely used regional model—WRF-Chem (the Weather Research and Forecasting model coupled with Chemistry). The O₃ and PM_2.5 mean biases of the two WRF-Chem simulations over the U.S. are 5–9 ppb and −3 μg/m³ during August and September 2020. The MUSICAv0 simulation has larger O₃ mean bias (11 ppb) but smaller PM_2.5 mean bias (−1 μg/m³) compared to the two WRF-Chem simulations. As indicated by spatial and temporal statistical measures, the variability in meteorological parameters (temperature, precipitation), and ozone and PM_2.5 are similar across a range of temporal and spatial scales in MUSICAv0 and WRF-Chem. We demonstrate the new capability of the global MUSICAv0 at regional scale through two examples—(a) plumes from western U.S. fires that passed through the domain boundary of WRF-Chem and were transported back into the domain and impacted air quality on the eastern U.S.; and (b) impact of stratospheric intrusion on the troposphere.