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Changes of ammonia concentrations in wintertime on the North China Plain from 2018 to 2020

Literature Reference
Peer Reviewed Literature

Yuexin He a,b, Yuepeng Pan a,b,c,*, Mengna Gu a,b, Qian Sun a,b, Qianqian Zhang d,**, Renjian Zhang e, Yuesi Wang a,b,c

a - State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry (LAPC), Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
b - University of Chinese Academy of Sciences, Beijing 100049, China
c - Center for Excellence in Urban Atmospheric Environment, Institute of Urban Environment, Chinese Academy of Sciences, Xiamen 361021, China
d - National Satellite Meteorological Center, China Meteorological Administration, Beijing 100081, China
e - Key Laboratory of Middle Atmosphere and Global Environment Observation (LAGEO), Xianghe Observatory of Whole Atmosphere, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China

January 28th, 2021

The reduced economic and social activities during the Chinese Spring Festival provide a unique experiment to evaluate reductions in anthropogenic NH3 emissions in China. However, quantifying this unique scenario is challenging as meteorology may mask the real changes in observed NH3 concentrations. Here, we applied a machine learning technique to decouple the effects of meteorology and confirmed that the real (deweathered) NH3 concentration dropped to a minimum during the Spring Festival in 2019 and 2020 at both urban (Beijing) and rural (Xianghe) sites on the North China Plain. Compared with the scenario without the Spring Festival effect, we predicted that NH3 concentrations in 2020 were 39.8% and 24.6% higher than the observed values at the urban and rural sites, respectively. The significant difference between the two sites indicates a larger reduction in anthropogenic NH3 emissions in urban areas than in rural areas due to the Spring Festival and lockdown measures of COVID-19. Future control strategies should consider the emissions of NH3 from the transportation, industrial and residential sectors, considering that agricultural emissions are minor in cold seasons.