PNNL

Abstract

In the U.S., emissions of greenhouse gases and air pollutants are often developed independently. Here, we describe the GReenhouse gas And Air Pollutant Emissions System (GRA2PES), which provides gridded emissions of fossil-fuel carbon dioxide (ffCO2) and 93 air quality (AQ) species for 17 combustion and non-combustion sectors, at 4 km × 4 km spatial resolution across the contiguous US. We find that the AQ emissions most spatially correlated with ffCO2 are nitrogen oxides (NOx, ? = 0.80), followed by sulfur dioxide (SO2, ? = 0.64), fine particulate matter (PM2.5, ? = 0.49), and carbon monoxide (CO, ? = 0.39). We evaluate GRA2PES ffCO2 emissions with an ensemble of publicly available regional and global inventories at national (NMB = +1.5%), state (NMB = +1.5%, R2 = 0.98), and urban (NMB = +12.0%, R2 = 0.97) scales. Nationally, the differences of publicly available inventories from the ensemble average range from -9.9% to +5.7%, and consistency diverges at state and urban scales. We simulate GRA2PES ffCO2 in a particle dispersion model and compare to measurements of radiocarbon (14C)-derived ffCO2 collected in Los Angeles (August 2021), and which suggests that GRA2PES ffCO2 are low by 23% for this city, although within model-observation differences across other publicly 3 available inventories (-44% to +94%). GRA2PES AQ/ffCO2 ratios converted to concentration space generally agree with field observations (NMB = 3%, log R2 = 0.92). Lastly, we present a method by which to utilize GRA2PES to derive AQ emission fluxes from ffCO2 emissions.