Causes of growing middle-to-upper tropospheric ozone over the northwest Pacific region

<p>Long-term ozone (O<span class="inline-formula"><sub>3</sub></span>) changes in the middle-to-upper troposphere are critical to climate radiative forcing and tropospheric O<span class="inline-formula"><sub>3</sub></span> pol...

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Main Authors: X. Ma, J. Huang, M. I. Hegglin, P. Jöckel, T. Zhao
Format: Article
Language:English
Published: Copernicus Publications 2025-01-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/25/943/2025/acp-25-943-2025.pdf
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author X. Ma
X. Ma
J. Huang
J. Huang
M. I. Hegglin
M. I. Hegglin
P. Jöckel
T. Zhao
author_facet X. Ma
X. Ma
J. Huang
J. Huang
M. I. Hegglin
M. I. Hegglin
P. Jöckel
T. Zhao
author_sort X. Ma
collection DOAJ
description <p>Long-term ozone (O<span class="inline-formula"><sub>3</sub></span>) changes in the middle-to-upper troposphere are critical to climate radiative forcing and tropospheric O<span class="inline-formula"><sub>3</sub></span> pollution. Yet, these changes remain poorly quantified through observations in East Asia. Concerns also persist regarding the data quality of the ozonesondes available at the World Ozone and Ultraviolet Radiation Data Centre (WOUDC) for this region. This study aims to address these gaps by analyzing O<span class="inline-formula"><sub>3</sub></span> soundings at four sites along the northwestern Pacific coastal region over the past 3 decades and by assessing their consistency with an atmospheric chemistry–climate model simulation. Utilizing the European Centre for Medium-Range Weather Forecasts (ECMWF) Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) nudged simulations, it is demonstrated that trends between model and ozonesonde measurements are overall consistent, thereby gaining confidence in the model's ability to simulate O<span class="inline-formula"><sub>3</sub></span> trends and confirming the utility of potentially imperfect observational data. A notable increase in O<span class="inline-formula"><sub>3</sub></span> mixing ratio around 0.29–0.82 ppb a<span class="inline-formula"><sup>−1</sup></span> extending from the middle troposphere to the upper troposphere is observed in both observations and model simulations between 1990 and 2020, primarily during spring and summer. The timing of these O<span class="inline-formula"><sub>3</sub></span> tongues is delayed when moving from south to north along the measurement sites, transitioning from late spring to summer. Investigation into the drivers of these trends using tagged model tracers reveals that O<span class="inline-formula"><sub>3</sub></span> of stratospheric origin (O<span class="inline-formula"><sub>3</sub></span>S) dominates the absolute O<span class="inline-formula"><sub>3</sub></span> mixing ratios over the middle-to-upper troposphere in the subtropics, contributing to the observed O<span class="inline-formula"><sub>3</sub></span> increases by up to 96 % (40 %) during winter (summer), whereas O<span class="inline-formula"><sub>3</sub></span> of tropospheric origin (O<span class="inline-formula"><sub>3</sub></span>T) governs the absolute value throughout the tropical troposphere and contributes generally much more than 60 % to the positive O<span class="inline-formula"><sub>3</sub></span> changes, especially during summer and autumn. During winter and spring, a decrease in O<span class="inline-formula"><sub>3</sub></span>S is partly counterbalanced by an increase in O<span class="inline-formula"><sub>3</sub></span>T in the tropical troposphere. This study highlights that the enhanced downward transport of stratospheric O<span class="inline-formula"><sub>3</sub></span> into the troposphere in the subtropics and a surge of tropospheric O<span class="inline-formula"><sub>3</sub></span> in the tropics are the two key factors driving the enhancement of O<span class="inline-formula"><sub>3</sub></span> in the middle-to-upper troposphere along the northwest Pacific region.</p>
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spelling doaj-art-fabd56519a9c48dfae9d97d5317a282d2025-01-27T09:04:26ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-01-012594395810.5194/acp-25-943-2025Causes of growing middle-to-upper tropospheric ozone over the northwest Pacific regionX. Ma0X. Ma1J. Huang2J. Huang3M. I. Hegglin4M. I. Hegglin5P. Jöckel6T. Zhao7Collaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, ChinaInstitute of Energy and Climate Research – Stratosphere (IEK-7), Forschungszentrum Jülich, Jülich, GermanyEnvironmental Modeling Center, NOAA National Centers for Environmental Prediction, College Park, MD, USACenter for Spatial Information Science and Systems, College of Science, George Mason University, Fairfax, VA 22030, USAInstitute of Energy and Climate Research – Stratosphere (IEK-7), Forschungszentrum Jülich, Jülich, GermanyDepartment of Meteorology, University of Reading, Reading, United KingdomDeutsches Zentrum für Luft- und Raumfahrt (DLR), Institut für Physik der Atmosphäre, Oberpfaffenhofen, GermanyCollaborative Innovation Center on Forecast and Evaluation of Meteorological Disasters, Key Laboratory for Aerosol-Cloud-Precipitation of China Meteorological Administration, Nanjing University of Information Science and Technology, Nanjing 210044, China<p>Long-term ozone (O<span class="inline-formula"><sub>3</sub></span>) changes in the middle-to-upper troposphere are critical to climate radiative forcing and tropospheric O<span class="inline-formula"><sub>3</sub></span> pollution. Yet, these changes remain poorly quantified through observations in East Asia. Concerns also persist regarding the data quality of the ozonesondes available at the World Ozone and Ultraviolet Radiation Data Centre (WOUDC) for this region. This study aims to address these gaps by analyzing O<span class="inline-formula"><sub>3</sub></span> soundings at four sites along the northwestern Pacific coastal region over the past 3 decades and by assessing their consistency with an atmospheric chemistry–climate model simulation. Utilizing the European Centre for Medium-Range Weather Forecasts (ECMWF) Hamburg (ECHAM)/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) nudged simulations, it is demonstrated that trends between model and ozonesonde measurements are overall consistent, thereby gaining confidence in the model's ability to simulate O<span class="inline-formula"><sub>3</sub></span> trends and confirming the utility of potentially imperfect observational data. A notable increase in O<span class="inline-formula"><sub>3</sub></span> mixing ratio around 0.29–0.82 ppb a<span class="inline-formula"><sup>−1</sup></span> extending from the middle troposphere to the upper troposphere is observed in both observations and model simulations between 1990 and 2020, primarily during spring and summer. The timing of these O<span class="inline-formula"><sub>3</sub></span> tongues is delayed when moving from south to north along the measurement sites, transitioning from late spring to summer. Investigation into the drivers of these trends using tagged model tracers reveals that O<span class="inline-formula"><sub>3</sub></span> of stratospheric origin (O<span class="inline-formula"><sub>3</sub></span>S) dominates the absolute O<span class="inline-formula"><sub>3</sub></span> mixing ratios over the middle-to-upper troposphere in the subtropics, contributing to the observed O<span class="inline-formula"><sub>3</sub></span> increases by up to 96 % (40 %) during winter (summer), whereas O<span class="inline-formula"><sub>3</sub></span> of tropospheric origin (O<span class="inline-formula"><sub>3</sub></span>T) governs the absolute value throughout the tropical troposphere and contributes generally much more than 60 % to the positive O<span class="inline-formula"><sub>3</sub></span> changes, especially during summer and autumn. During winter and spring, a decrease in O<span class="inline-formula"><sub>3</sub></span>S is partly counterbalanced by an increase in O<span class="inline-formula"><sub>3</sub></span>T in the tropical troposphere. This study highlights that the enhanced downward transport of stratospheric O<span class="inline-formula"><sub>3</sub></span> into the troposphere in the subtropics and a surge of tropospheric O<span class="inline-formula"><sub>3</sub></span> in the tropics are the two key factors driving the enhancement of O<span class="inline-formula"><sub>3</sub></span> in the middle-to-upper troposphere along the northwest Pacific region.</p>https://acp.copernicus.org/articles/25/943/2025/acp-25-943-2025.pdf
spellingShingle X. Ma
X. Ma
J. Huang
J. Huang
M. I. Hegglin
M. I. Hegglin
P. Jöckel
T. Zhao
Causes of growing middle-to-upper tropospheric ozone over the northwest Pacific region
Atmospheric Chemistry and Physics
title Causes of growing middle-to-upper tropospheric ozone over the northwest Pacific region
title_full Causes of growing middle-to-upper tropospheric ozone over the northwest Pacific region
title_fullStr Causes of growing middle-to-upper tropospheric ozone over the northwest Pacific region
title_full_unstemmed Causes of growing middle-to-upper tropospheric ozone over the northwest Pacific region
title_short Causes of growing middle-to-upper tropospheric ozone over the northwest Pacific region
title_sort causes of growing middle to upper tropospheric ozone over the northwest pacific region
url https://acp.copernicus.org/articles/25/943/2025/acp-25-943-2025.pdf
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