We present decadal trend estimates of surface carbon monoxide (CO), simulated using the atmospheric chemistry general circulation model ECHAM5/MESSy (EMAC) based on the emission scenarios, Representative Concentration Pathways (RCP) 8.5 for anthropogenic activity and Global Fire Emissions Database (GFED) v3.1 for biomass burning from 2001 through 2010. The spatial distribution of the modelled surface CO is evaluated with monthly Measurements Of Pollution In The Troposphere (MOPITT) thermal infrared product. The global means of correlation coefficient and relative bias for the 2001–2010 are 0.95 and −4.29%, respectively. We also find a reasonable correlation (<i>R</i> = 0.78) between the trends of EMAC surface CO and full 10 year monthly records from ground-based observation (World Data Centre for Greenhouse Gases, WDCGG). Over Western Europe, Eastern USA, and Northern Australia, the significant decreases of EMAC surface CO are estimated at −35.5 ± 5.8, −59.6 ± 9.1, and −13.7 ± 9.5 ppbv decade<sup>−1</sup>, respectively, with a 95% confidence interval. In contrast, the surface CO increases by +8.9 ± 4.8 ppbv decade<sup>−1</sup> over South Asia. A high correlation (<I>R</i> = 0.92) between the significant changes in EMAC-simulated surface CO and total emission flux shows that the significant regional trends are attributed to the changes in primary/direct emissions from both anthropogenic activity and biomass burning. In particular, increasing trends of surface hydroxyl radical (OH) partially contribute to the decreasing trends of surface CO in Western Europe and Eastern USA.
Yoon, J., & Pozzer, A. (2014). Model-simulated trend of surface carbon monoxide for the 2001-2010 decade. Atmospheric Chemistry and Physics, 14(19), 10465–10482. https://doi.org/10.5194/acp-14-10465-2014