Rapid increase in tropospheric ozone over Southeast Asia attributed to changes in precursor emission source regions and sectors. (1st July 2023)

• Record Type: Journal Article
• Authors: Li, Su; Yang, Yang; Wang, Hailong; Li, Pengwei; Li, Ke; Ren, Lili; Wang, Pinya; Li, Baojie; Mao, Yuhao; Liao, Hong
• Is Part Of: Atmospheric environment. Volume 304(2023)
• Publication Date: 2023-07-01
• Subjects: Air -- Pollution -- Periodicals; Air -- Pollution -- Meteorological aspects -- Periodicals; 551.51
• DOI: 10.1016/j.atmosenv.2023.119776
• Languages: English
• ISSNs: 1352-2310

Abstract

Abstract: Observations indicate that tropospheric ozone (O3 ) concentrations over Southeast Asia have been increasing rapidly since the 1990s. Here, we quantify source contributions from geographical regions and emission sectors of the two distinct types of O3 precursors, i.e., nitrogen oxides (NOx ) and volatile organic compounds (VOCs), to the increase in tropospheric O3 in Southeast Asia during 1990–2019 using an O3 source tagging technique implemented in a global chemistry-climate model. The results show that although local anthropogenic emission of NOx in Southeast Asia only contributes 18% of the annual averaged near-surface O3 concentration, the increase in local NOx emission dominates the increasing trend of O3 concentration in Southeast Asia, accounting for 107% of the regional averaged trend of 1.07 ppb decade −1 . Increases in NOx emissions from East Asia and South Asia explain 29% of the increasing trend, but 9% is offset by the emission reduction in North America. The vertical O3 trends in the troposphere contributed by individual source regions are consistent with those near the surface. Ground transportation is responsible for 79% of the rapid O3 increase, followed by 39% contribution from international shipping. Because an increase in anthropogenic NOx emissions enhances the O3 production efficiency by VOCs, the increase in O3 concentrations in Southeast Asia is thereby largely contributed by methane and biogenic VOCs. Graphical abstract: Image 1 Highlights: Source apportionments of tropospheric ozone in Southeast Asia from 1990 to 2019 are quantified with a tagging technique. Significant increase in local NOx emissions is the reason for the increase in tropospheric ozone in Southeast Asia. NOx emissions from ground transportation and international shipping explain the rapid rise in ozone concentrations. Increasing anthropogenic NOx emissions enhance the efficiency of ozone production by VOCs.