Anthropogenic Carbon Monoxide Emissions During 2014–2020 in China Constrained by In Situ Ground Observations

Abstract China has been actively reducing anthropogenic air pollutant emissions over the past decade and is about to embark on the next phase of air quality management. Carbon monoxide (CO) is an ideal indicator of primary pollutants from combustion sources. A comprehensive assessment of the current situation of anthropogenic CO emissions can inform the implementation of future reduction policies. This work aims to determine the changes of anthropogenic CO emissions in mainland China from 2014 to 2020 at 0.2° × 0.2° spatial resolution. Hourly CO observations from over 1,600 national control sites were combined with Lagrangian dispersion modeling and multisectoral emission inventories in a Bayesian inversion framework, to determine monthly CO emissions. From 2014 to 2020, the average annual anthropogenic CO emission in mainland China was 473.6 ± 117.2 Tg a −1 , which is 2.5 times higher than the prior emission. Northwest China stands out as the most underestimated region with a relative difference of an astonishing 6.3 times between prior and posterior emissions. The emissions generally decreased by 32.0% from 2014 to 2020, but with a clear rebound in 2017 and 2018, and Yunnan in the southwest and Xinjiang in the northwest are the most pronounced rebound provinces. Optimizing the management of direct emissions in the future requires not only focusing on key urban agglomerations but also strengthening controls in remote provinces.