Surface and tropospheric ozone over East Asia and Southeast Asia from observations: distributions, trends, and variability

Abstract. The high level of ozone throughout the troposphere is an emerging concern for East Asia and Southeast Asia. Here, we analyze available surface ozone measurements from the past two decades (2005–2021) over eight countries, with 10 ozonesonde and aircraft measurements within this region. At the surface, the seasonal mean ozone over 2017–2021 varies from 30 nmol mol−1 (i.e., 30 ppb) in Southeast Asia to 75 nmol mol−1 in summer in northern China. The metric of seasonal 95th percentile ozone can identify the multiple hot spots of ozone pollution of over 85 nmol mol−1 in Southeast Asia. The new World Health Organization (WHO) peak-season ozone standard indicates that both East Asia and Southeast Asia face a widespread risk of long-term exposure. The surface ozone increase in South Korea and Southeast Asia from 2005 was leveling off or even decreasing in the past decade, while the ozone increase in the 2000s over China has amplified since 2013. Surface ozone trends in Japan and Mongolia were flat in the past decade. In the troposphere, the available measurements show an overall increasing tendency at different altitudes from a three-decade perspective, although the trend in the past decade remains unclear due to data availability. The difference in the tropospheric ozone level between East Asia and Southeast Asia is likely due to the high background ozone from the stratospheric intrusion over Northeast Asia. In terms of ozone controls, our results suggest that anthropogenic emissions determine the occurrence of high ozone levels, but the underappreciated strong ozone climate penalty, particularly over Southeast Asia, will make ozone controls harder under a warmer climate.

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Publication Details

Journal
Atmospheric chemistry and physics
Published
2025-09-30
DOI
https://doi.org/10.5194/acp-25-11575-2025
Primary Topic
Atmospheric Ozone and Climate
Type
article
Field-Weighted Citation Impact
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article

Surface and tropospheric ozone over East Asia and Southeast Asia from observations: distributions, trends, and variability

Ja‐Ho Koo, Taegyung Lee, Yixuan Gu, Xiao Lu et al.
Atmospheric chemistry and physics
Atmospheric Ozone and Climate
article

Surface and tropospheric ozone over East Asia and Southeast Asia from observations: distributions, trends, and variability

Ja‐Ho Koo, Taegyung Lee, Yixuan Gu, Xiao Lu, Yugo Kanaya, Wenhao Qiao, Meehye Lee, Teerachai Amnuaylojaroen, Zhiqiang Ma, Danyuting Zhang, Junsu Gil, Wenqing Zhao, Likun Xue, Rong Tan, Juseon Bak, Ke Li, Xiaopu Lyu, Tatsuya Nagashima, Mohd Talib Latif, Joowan Kim, Jianming Xu, Shaojia Fan, Jinqiang Zhang, Hong Liao, Yufen Wang, Minglong Tang
article en

Abstract

Abstract. The high level of ozone throughout the troposphere is an emerging concern for East Asia and Southeast Asia. Here, we analyze available surface ozone measurements from the past two decades (2005–2021) over eight countries, with 10 ozonesonde and aircraft measurements within this region. At the surface, the seasonal mean ozone over 2017–2021 varies from 30 nmol mol−1 (i.e., 30 ppb) in Southeast Asia to 75 nmol mol−1 in summer in northern China. The metric of seasonal 95th percentile ozone can identify the multiple hot spots of ozone pollution of over 85 nmol mol−1 in Southeast Asia. The new World Health Organization (WHO) peak-season ozone standard indicates that both East Asia and Southeast Asia face a widespread risk of long-term exposure. The surface ozone increase in South Korea and Southeast Asia from 2005 was leveling off or even decreasing in the past decade, while the ozone increase in the 2000s over China has amplified since 2013. Surface ozone trends in Japan and Mongolia were flat in the past decade. In the troposphere, the available measurements show an overall increasing tendency at different altitudes from a three-decade perspective, although the trend in the past decade remains unclear due to data availability. The difference in the tropospheric ozone level between East Asia and Southeast Asia is likely due to the high background ozone from the stratospheric intrusion over Northeast Asia. In terms of ozone controls, our results suggest that anthropogenic emissions determine the occurrence of high ozone levels, but the underappreciated strong ozone climate penalty, particularly over Southeast Asia, will make ozone controls harder under a warmer climate.

Atmospheric chemistry and physicsVol. 25(19)
Japan Agency for Marine-Earth Science and Technology (JP), China Meteorological Administration (CN), Hong Kong Baptist University (HK), Shandong University (CN), Sun Yat-sen University (CN), Yonsei University (KR), Chinese Academy of Sciences (CN), National Institute for Environmental Studies (JP), Nanjing University of Information Science and Technology (CN), Kongju National University (KR), University of Phayao (TH), Korea Environment Institute (KR), Shanghai Meteorological Bureau (CN), Institute of Atmospheric Physics (CN), Pusan National University (KR), National University of Malaysia (MY)
Openalex Percentile: Top 68%
Atmospheric Ozone and Climate
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