Observing Downwind Structures of Urban HCHO Plumes From Space: Implications to Non‐Methane Volatile Organic Compound Emissions

• Published in: Geophysical research letters Vol. 50; no. 24
• Main Authors: Zuo, Xiaoxing, Sun, Wenfu, Smedt, Isabelle, Li, Xicheng, Liu, Song, Pu, Dongchuan, Sun, Shuai, Li, Juan, Chen, Yuyang, Fu, Weitao, Zhang, Peng, Li, Yali, Yang, Xin, Fu, Tzung‐May, Shen, Huizhong, Ye, Jianhuai, Wang, Chen, Zhu, Lei
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.12.2023; Wiley
• Subjects: Air; Air monitoring; Air quality; Cities; Emission measurements; Emissions; HCHO; Methane; Monitoring instruments; non‐methane volatile organic compounds; Organic compounds; Outdoor air quality; Plumes; Satellite observation; Satellite tracking; Satellites; TROPOMI; Urban air; Urban air quality; Urban areas; urban plumes; VOCs; Volatile organic compound emissions; Volatile organic compounds; Wind
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2023GL106062

Non‐methane volatile organic compounds (NMVOCs) have a significant impact on air quality in urban areas. Detecting NMVOCs emission with its proxy HCHO on urban scales from space, however, has been limited by the lack of discernible enhancement. Here we show clear urban HCHO plumes from 16 cities over the globe by rotating TROPOspheric Monitoring Instrument HCHO pixels according to wind directions. We fit the downwind structure of the plumes with the exponentially modified Gaussian approach to quantify urban HCHO effective production rates between 7.0 and 88.5 mol s−1. Our results are in line with total NMVOC emissions from the EDGAR inventory (r = 0.76). Our work offers a new measure of total NMVOC emissions from urban areas and highlights the potential of satellite HCHO data to provide new information for monitoring urban air quality. Plain Language Summary Non‐methane volatile organic compounds (NMVOCs) play an important role in urban air quality. Formaldehyde (HCHO) satellite observations have been shown to be able to reliably track and quantify NMVOC emissions at global and regional scales. Here, we use state‐of‐the‐art satellite sensors to quantify effective HCHO production rates in 16 global cities and further constrain total NMVOC emissions. Our results are broadly consistent with current emissions inventories, implying that satellites may be able to provide new information for urban air studies. Key Points We show clear urban HCHO plumes from 16 cities over the globe by relating satellite pixels with wind fields We obtain urban effective HCHO production rates by fitting the downwind structure of HCHO plumes Satellite‐based effective HCHO production rates provide potential measures of total non‐methane volatile organic compound emissions