Modeling urban pollutant transport at multiple resolutions: impacts of turbulent mixing

<p>Air pollution in cities impacts public health and climate. Turbulent mixing is crucial in pollutant formation and dissipation, yet current atmospheric models struggle to accurately represent it. Turbulent mixing intensity varies with model resolution, which has rarely been analyzed. To inve...

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Main Authors: Z. Yang, Q. Du, Q. Yang, C. Zhao, G. Li, Z. Xia, M. Xu, R. Yuan, Y. Li, K. Xia, J. Gu, J. Feng
Format: Article
Language:English
Published: Copernicus Publications 2025-08-01
Series:Atmospheric Chemistry and Physics
Online Access:https://acp.copernicus.org/articles/25/8831/2025/acp-25-8831-2025.pdf
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author Z. Yang
Q. Du
Q. Yang
C. Zhao
C. Zhao
C. Zhao
G. Li
Z. Xia
M. Xu
R. Yuan
Y. Li
K. Xia
J. Gu
J. Feng
author_facet Z. Yang
Q. Du
Q. Yang
C. Zhao
C. Zhao
C. Zhao
G. Li
Z. Xia
M. Xu
R. Yuan
Y. Li
K. Xia
J. Gu
J. Feng
author_sort Z. Yang
collection DOAJ
description <p>Air pollution in cities impacts public health and climate. Turbulent mixing is crucial in pollutant formation and dissipation, yet current atmospheric models struggle to accurately represent it. Turbulent mixing intensity varies with model resolution, which has rarely been analyzed. To investigate turbulent mixing variations at multiple resolutions and their implications for urban pollutant transport, we conducted experiments using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) at resolutions of 25, 5, and 1 km. The simulated meteorological fields and black carbon (BC) concentrations are compared with observations. Differences in turbulent mixing across multiple resolutions are more pronounced at night, resulting in noticeable variations in BC concentrations. BC surface concentrations decrease as resolution increases from 25 to 5 km and further to 1 km, but they are similar at 5 and 1 km resolutions. Enhanced planetary boundary layer (PBL) mixing coefficients and vertical wind flux at higher resolutions reduce BC surface concentration overestimations. The 1 km resolution parameterized lower mixing coefficients than 5 km but resolved more small-scale eddies, leading to similar near-surface turbulent mixing at both resolutions, while the intensity at higher altitudes was greater at 1 km. This caused BC to be transported higher and farther, increasing its atmospheric lifetime and column concentrations. Variations in mixing coefficients are partly attributed to differences in land use and terrain, with higher resolutions providing more detailed information that enhances PBL mixing coefficients, while grid size remains crucial in regions with more gradual terrain and land use changes. This study interprets how turbulent mixing affects simulated urban pollutant diffusion at multiple resolutions.</p>
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institution Kabale University
issn 1680-7316
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publishDate 2025-08-01
publisher Copernicus Publications
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spelling doaj-art-d07673a556ab4ffba168eced6ed7fb922025-08-20T04:00:49ZengCopernicus PublicationsAtmospheric Chemistry and Physics1680-73161680-73242025-08-01258831885710.5194/acp-25-8831-2025Modeling urban pollutant transport at multiple resolutions: impacts of turbulent mixingZ. Yang0Q. Du1Q. Yang2C. Zhao3C. Zhao4C. Zhao5G. Li6Z. Xia7M. Xu8R. Yuan9Y. Li10K. Xia11J. Gu12J. Feng13Deep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaLaoshan Laboratory, Qingdao, ChinaCAS Center for Excellence in Comparative Planetology, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaSchool of Atmospheric Physics, Nanjing University of Information Science and Technology, Nanjing, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, ChinaDeep Space Exploration Laboratory/School of Earth and Space Sciences/CMA-USTC Laboratory of Fengyun Remote Sensing/State Key Laboratory of Fire Science/Institute of Advanced Interdisciplinary Research on High-Performance Computing Systems and Software, University of Science and Technology of China, Hefei, China<p>Air pollution in cities impacts public health and climate. Turbulent mixing is crucial in pollutant formation and dissipation, yet current atmospheric models struggle to accurately represent it. Turbulent mixing intensity varies with model resolution, which has rarely been analyzed. To investigate turbulent mixing variations at multiple resolutions and their implications for urban pollutant transport, we conducted experiments using the Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) at resolutions of 25, 5, and 1 km. The simulated meteorological fields and black carbon (BC) concentrations are compared with observations. Differences in turbulent mixing across multiple resolutions are more pronounced at night, resulting in noticeable variations in BC concentrations. BC surface concentrations decrease as resolution increases from 25 to 5 km and further to 1 km, but they are similar at 5 and 1 km resolutions. Enhanced planetary boundary layer (PBL) mixing coefficients and vertical wind flux at higher resolutions reduce BC surface concentration overestimations. The 1 km resolution parameterized lower mixing coefficients than 5 km but resolved more small-scale eddies, leading to similar near-surface turbulent mixing at both resolutions, while the intensity at higher altitudes was greater at 1 km. This caused BC to be transported higher and farther, increasing its atmospheric lifetime and column concentrations. Variations in mixing coefficients are partly attributed to differences in land use and terrain, with higher resolutions providing more detailed information that enhances PBL mixing coefficients, while grid size remains crucial in regions with more gradual terrain and land use changes. This study interprets how turbulent mixing affects simulated urban pollutant diffusion at multiple resolutions.</p>https://acp.copernicus.org/articles/25/8831/2025/acp-25-8831-2025.pdf
spellingShingle Z. Yang
Q. Du
Q. Yang
C. Zhao
C. Zhao
C. Zhao
G. Li
Z. Xia
M. Xu
R. Yuan
Y. Li
K. Xia
J. Gu
J. Feng
Modeling urban pollutant transport at multiple resolutions: impacts of turbulent mixing
Atmospheric Chemistry and Physics
title Modeling urban pollutant transport at multiple resolutions: impacts of turbulent mixing
title_full Modeling urban pollutant transport at multiple resolutions: impacts of turbulent mixing
title_fullStr Modeling urban pollutant transport at multiple resolutions: impacts of turbulent mixing
title_full_unstemmed Modeling urban pollutant transport at multiple resolutions: impacts of turbulent mixing
title_short Modeling urban pollutant transport at multiple resolutions: impacts of turbulent mixing
title_sort modeling urban pollutant transport at multiple resolutions impacts of turbulent mixing
url https://acp.copernicus.org/articles/25/8831/2025/acp-25-8831-2025.pdf
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