摘要：Abstract. Atmospheric carbon monoxide (CO) concentrations have beendecreasing since 2000, as observed by both satellite- and ground-basedinstruments, but global bottom-up emission inventories estimate increasinganthropogenic CO emissions concurrently. In this study, we use amulti-species atmospheric Bayesian inversion approach to attributesatellite-observed atmospheric CO variations to its sources and sinks inorder to achieve a full closure of the global CO budget during 2000–2017.Our observation constraints include satellite retrievals of the total columnmole fraction of CO, formaldehyde (HCHO), and methane (CH4) that areall major components of the atmospheric CO cycle. Three inversions (i.e.,2000–2017, 2005–2017, and 2010–2017) are performed to use the observationdata to the maximum extent possible as they become available and assess theconsistency of inversion results to the assimilation of more trace gasspecies. We identify a declining trend in the global CO budget since 2000(three inversions are broadly consistent during overlapping periods), drivenby reduced anthropogenic emissions in the US and Europe (both likely fromthe transport sector), and in China (likely from industry and residentialsectors), as well as by reduced biomass burning emissions globally,especially in equatorial Africa (associated with reduced burned areas). Weshow that the trends and drivers of the inversion-based CO budget are notaffected by the inter-annual variation assumed for prior CO fluxes. Allthree inversions contradict the globalbottom-up inventories in the world's top two emitters: for the sign ofanthropogenic emission trends in China (e.g., here -0.8±0.5 % yr−1 since 2000, while the prior gives 1.3±0.4 % yr−1)and for the rate of anthropogenic emission increase in South Asia (e.g.,here 1.0±0.6 % yr−1 since 2000, smaller than 3.5±0.4 % yr−1 in the prior inventory). The posterior model COconcentrations and trends agree well with independent ground-basedobservations and correct the prior model bias. The comparison of the threeinversions with different observation constraints further suggests that themost complete constrained inversion that assimilates CO, HCHO, and CH4has a good representation of the global CO budget, and therefore matches bestwith independent observations, while the inversion only assimilating COtends to underestimate both the decrease in anthropogenic CO emissions andthe increase in the CO chemical production. The global CO budget data fromall three inversions in this study can be accessed fromhttps://doi.org/10.6084/m9.figshare.c.4454453.v1 (Zheng et al., 2019).
