- Conference Proceedings Paper
Abstract: High-resolution simulations are essential to resolve fine-scale air pollution patterns due to localized emissions, nonlinear chemical feedbacks, and complex meteorology. However, high-resolution global simulations of air quality remain rare, especially of the Global South. Here, we exploit recent developments to the GEOS-Chem community model in its high performance implementation (GCHP) to conduct one-year simulations in 2015 at cubed-sphere C360 (~ 25km) and C48 (~ 200km) resolutions. We investigate the resolution dependence of population exposure and sectoral contributions to surface PM2.5 and NO2 focusing on understudied regions. Our results indicate pronounced spatial heterogeneity with global mean population-weighted normalized root mean square error (PW-NRMSE) at C48 of for primary (50% - 105%) and secondary (26% - 36%) PM2.5 species. Under-represented regions are more sensitive to spatial resolution resulting from sparse pollution hotspots, with PW-NRMSE for PM2.5 in the Global South (34%) 1.3 times higher than globally (25%). The spatial heterogeneity in southern cities (50%) is substantially higher than the more typically clustered northern cities (27%). High-resolution simulations also change the relative importance of emission sectors for both black carbon and NO2 in the Global South. Overall, spatial gradients of population exposure and sectoral contributions are artificially reduced with coarse simulations, especially in the Global South.