Can Global Chemistry-Climate Models Capture Salient Features of an Urban Atmosphere?

In recent decades, chemical transport models have been widely used for regional air quality studies worldwide. While these models offer a comprehensive approach for atmospheric chemistry and transport, they rely on global chemistry-climate models and reanalysis products with varying dynamics and resolutions for initial and boundary conditions. A Global Chemistry-Climate Model with Regional Refinement provides a unified modeling framework capable of simulating both large-scale atmospheric phenomena and regional air quality with consistent dynamics. In this study, we utilize the Multi-Scale Infrastructure for Chemistry and Aerosols Version 0 (MUSICAv0), a global chemistry-climate model with regional refinement at 7 km resolution across Arizona, to assess its performance in modeling ozone pollution in Phoenix, an arid city with diverse precursors, including NO_x, anthropogenic, and biogenic VOCs for July and August 2020. We conducted multiple simulations incorporating different anthropogenic emissions—such as CAMS-GLOB-ANT emissions and the National Emission Inventory (NEI) and varying chemical mechanisms, including MOZART TS1.2 and MOZART TS2, to investigate their impact on surface ozone levels and its precursors. Additionally, we compared MUSICAv0 simulations to WRF-Chem simulations at 9 km and 3 km horizontal resolutions to evaluate the influence of resolution on the model’s ability to capture NO_x- and VOC-limited regimes. Our results are validated against satellite retrievals of HCHO, NO₂, and CO from the Tropospheric Monitoring Instrument (TROPOMI), as well as ground-based observations from the USEPA Air Quality System and Photochemical Assessment Monitoring Stations (PAMS). The result of this study highlights the performance of MUSICAv0 for diurnal variation of ozone and its precursors in a city-scale study.