CO Emissions Inferred From Surface CO Observations Over China in December 2013 and 2017. Issue 7 (31st March 2020)

• Record Type: Journal Article
• Authors: Feng, Shuzhuang; Jiang, Fei; Wu, Zheng; Wang, Hengmao; Ju, Weimin; Wang, Haikun
• Is Part Of: Journal of geophysical research. Volume 125:Issue 7(2020)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2020-03-31
• Subjects: EnKF data assimilation -- CO emission -- inversion -- WRF/CMAQ model -- emission changes; Atmospheric physics -- Periodicals; Geophysics -- Periodicals; 551.5
• DOI: 10.1029/2019JD031808
• Languages: English
• ISSNs: 2169-897X

Abstract

Abstract: China has implemented active clean air policies in recent years, and the spatiotemporal patterns of major pollutant emissions have changed substantially. In this study, we construct a regional air pollution data assimilation system based on the WRF/CMAQ model and ensemble Kalman filter algorithm to quantitatively optimize gridded CO emissions using hourly surface CO measurements over China. The Multi‐resolution Emission Inventory of China CO emission inventories in December 2012 and 2016 are treated as prior emissions, and the CO emissions in December 2013 and 2017 are optimized using the CO observations of December of 2013 and 2017, respectively. The results show that in both periods, assimilation of CO observations significantly improves the CO simulations and emission estimates. Assimilation increases the CO emissions in most areas of mainland China, especially in northern China, and the spatial patterns of the increases in the two periods are similar. Overall, the posterior CO emissions in December 2017 are 17% lower than those in December 2013. Large emission decreases are mainly found in most key urban areas and developed regions, and emission increases are mainly located in their surrounding areas and certain central and western regions, which might reflect the emission migration from developed regions or urban areas to developing regions or surrounding areas. These changes are not found in the prior emissions but are basically consistent with the emission control strategies and industrial transformation and upgrade phenomena in recent years, indicating that our CO assimilation system could successfully capture the temporal and spatial variations. Plain Language Summary: CO emissions over China in December 2013 and 2017 were optimized using surface hourly CO observations, and the emission changes between these two periods were presented. We found that there were large emission decreases in key urbans and developed regions, and increases in their surrounding areas and some central and western regions, which were basically consistent with the emission control strategies and industrial transformation in recent years, might reflect the emission migration. Key Points: A regional air pollution data assimilation system based on WRF/CMAQ and EnKF is constructed Overall, the CO emissions are reduced by 17% between December 2013 and 2017 over the whole mainland of China The emissions migration is found in the posterior emissions but not shown in the prior emissions