Clustering Analysis on Drivers of O3 Diurnal Pattern and Interactions with Nighttime NO3 and HONO

Atmosphere

Chuanqi Gu¹  Bin Zhou¹  Ruifeng Zhang¹  Shanshan Wang¹  Sanbao Zhang¹  Aimon Tanvir¹  Xue Wang¹ 

[1] Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention (LAP3), Department of Environmental Science and Engineering, Fudan University, Shanghai 200438, China;

关键词: ozone pollution;    photochemical reaction;    nighttime ozone;    clustering;    LP-DOAS;   

DOI  :  10.3390/atmos13020351

来源: DOAJ

【 摘 要 】

The long-path differential optical absorption spectroscopy (LP-DOAS) technique was deployed in Shanghai to continuously monitor ozone (O₃), formaldehyde (HCHO), nitrogen dioxide (NO₂), nitrous acid (HONO), and nitrate radical (NO₃) mixing ratios from September 2019 to August 2020. Through a clustering method, four typical clusters of the O₃ diurnal pattern were identified: high during both the daytime and nighttime (cluster 1), high during the nighttime but low during the daytime (cluster 2), low during both the daytime and nighttime (cluster 3), and low during the nighttime but high during the daytime (cluster 4). The drivers of O₃ variation for the four clusters were investigated for the day- and nighttime. Ambient NO caused the O₃ gap after midnight between clusters 1 and 2 and clusters 3 and 4. During the daytime, vigorous O₃ generation (clusters 1 and 4) was found to accompany higher temperature, lower humidity, lower wind speed, and higher radiation. Moreover, O₃ concentration correlated with HCHO for all clusters except for the low O₃ cluster 3, while O₃ correlated with HCHO/NO_x, but anti-correlated with NO_x for all clusters. The lower boundary layer height before midnight hindered O₃ diffusion and accordingly determined the final O₃ accumulation over the daily cycle for clusters 1 and 4. The interactions between the O₃ diel profile and other atmospheric reactive components established that higher HONO before sunrise significantly promoted daytime O₃ generation, while higher daytime O₃ led to a higher nighttime NO₃ level. This paper summarizes the interplays between day- and nighttime oxidants and oxidation products, particularly the cause and effect for daytime O₃ generation from the perspective of nighttime atmospheric components.

【 授权许可】

Unknown