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https://doi.org/10.5194/egusphere-2022-1271
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/egusphere-2022-1271
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
06 Dec 2022
| 06 Dec 2022
Rethinking the role of transport and photochemistry in regional ozone pollution: Insights from ozone concentration and mass budgets
Abstract. Understanding the role of transport and photochemistry is essential to alleviate ambient ozone pollution. However, ozone budget and source apportionment studies often report conflicting conclusions — Local photochemistry is the main cause of ozone pollution based on the analyses of the former, while contrary, non-local ozone transported to the region accounts for the majority in the latter results. In order to explore its potential causes, we calculated the contributions of both processes to the variations of mean ozone concentration and total ozone mass (the corresponding budgets are noted as ozone concentration and mass budget, respectively) within the atmospheric boundary layer (ABL) of the Pearl River Delta (PRD), China, based on the modelling results of WRF-CMAQ. Quantified results show that photochemistry drives the rapid increase of ozone concentrations in the daytime, whereas transport, especially the vertical exchange near the ABL top, controls the ozone mass budget. The changes in transport contributions in ozone budgets indicate the influences of the ABL diurnal cycle and regional wind fields, including prevailing winds and local circulations (sea breezes), on regional ozone pollution. Though transport in our simulations had a relatively limited effect on ozone concentration, its high contribution to ozone mass increase in the morning determined that most ozone in the PRD emanated from the outer regions. Consequently, the role of transport and photochemistry in ozone pollution may differ, depending on which of the two budgets is concerned. For future studies targeting ozone and other pollutants with moderately long atmospheric lifetimes, we suggest that attention should be paid to budget-type selections.
How to cite. Qu, K., Wang, X., Cai, X., Yan, Y., Jin, X., Vrekoussis, M., Shen, J., Xiao, T., Zeng, L., and Zhang, Y.: Rethinking the role of transport and photochemistry in regional ozone pollution: Insights from ozone concentration and mass budgets, EGUsphere [preprint], https://doi.org/10.5194/egusphere-2022-1271, 2022.
Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this preprint. The responsibility to include appropriate place names lies with the authors.
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Journal article(s) based on this preprint
13 Jul 2023
Rethinking the role of transport and photochemistry in regional ozone pollution: insights from ozone concentration and mass budgets
Kun Qu, Xuesong Wang, Xuhui Cai, Yu Yan, Xipeng Jin, Mihalis Vrekoussis, Maria Kanakidou, Guy P. Brasseur, Jin Shen, Teng Xiao, Limin Zeng, and Yuanhang Zhang
Atmos. Chem. Phys., 23, 7653–7671, https://doi.org/10.5194/acp-23-7653-2023, https://doi.org/10.5194/acp-23-7653-2023, 2023
Short summary
Short summary
Basic understandings of ozone processes, especially transport and chemistry, are essential to support ozone pollution control, but studies often have different views on their relative importance. We developed a method to quantify their contributions in the ozone mass and concentration budgets based on the WRF-CMAQ model. Results in a polluted region highlight the differences between two budgets. For future studies, two budgets are both needed to fully understand the effects of ozone processes.
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
-
RC1: 'Comment on egusphere-2022-1271', Anonymous Referee #1, 19 Jan 2023
General Comments
- Understanding the processes controlling the O3 concentration in a specific area is important to design emission reduction strategies to reduce the harmful effects of tropospheric O3. This paper focuses on two processes that take place in the O3 cycle: transport and photochemistry.
- The paper discusses two methodological approaches to understand two O3 processes (transport and photochemistry) which are the O3 budget and the O3 source apportionment. Authors claims that there is a contradictory view on the role of transport and photochemistry in O3 pollution between the budget calculation studies and O3 source apportionment studies, because both studies provide different information. In my point of view, they are two different approaches difficult to compare, so it is normal they provide different results. However, as the authors show in the paper it is possible to learn from the both of them.
- I think the paper is organized in a way that it does not help to understand its objective and methodology, even it shows a hard work behind. So, in my opinion, this manuscript was hard to follow and understand, and consequently to review. Furthermore, it could help if authors improve the readability of the text. Overall, there are too many pronouns and missing nouns that make difficult to follow the main idea of some sentences. Authors should review the text carefully and provide a more accurate reference to key concepts, also being consistent in the way they do it along the manuscript.
I would suggest few clarifications and corrections:
Specific comments
- Abstract: difficult to get the important of the problem from the four first lines.
- The abstract does not help to understands the objective and the methodology approach. Ozone budget calculation and O3 source apportionment studies seems two different type of approaches difficult to compare, so it is normal the provide different results.
- Line 29: you mention two budgets, but you have not introduced them in the abstract. Is that related with the two type of studies?
- Line 74: the subject of that sentence “O3 source” does not make sence. Could your elaborate more the idea in that sentence.
- Line 88: “O3 source studies”. Use the same set of words to mention these studies. I guess in this case you want to say “O3 source apportionment studies”. The same comment in lines 90-91, “source apportionment studies” and “O3 budget studies”.
- Line 93: “CTM are capable of reproducing O3 processes”. In this sentence, you are attributing too much credibility to CTM, but models are not perfect and not always reproduce all the processes. I would be more realistic with what CTM can do, so I would suggest to rewrite this sentence.
- Line 220: “acceptable” from which point of view?
- Line 221: “reasonable” from which point of view?
- Lines 93-103 is specifically to CMAQ, it does not apply to any Eulerian CTMS (i.e. not CTM has a PA module).
- Line 121: “Horizontal transport through the borders of the PRD in four directions”. Is that correct? I guess you have two horizontal direction (x and y).
- Section 2.5 Model setup and validation. Even the model setup is described in the Qu et al. (2021) some basic details should be provided in the text, for example CMAQ and WRF version. Furthermore, the section is named “validation”. You mainly referenced Qu et al. (2021) but readers would appreciate a paragraph describing “why” we can trust on your modeling system’s results. The evaluation of ABL height with IAGOS measurements is very interesting. Could you elaborate more on the problems with CMAQ during the night?
- Line 236-237: Is that sentence well written?
- Source apportion method: Could you comment on the brute force disadvantages for O3 source apportionment calculation? Could CMAQ-ISAM source apportionment method improve your results?
- Conclusions: “This study concluded that transport and gas-phase chemistry play the main role in the O3 concentration and mass budgets”. Is it not new, right? Could you elaborate more this sentence as the main conclusion of this work.
- Conclusions: Could you elaborate more in the biases in your modelling results? For example, discussing the uncertainties in your emission data, meteorological fields, chemical and meteorological boundary conditions, chemistry in the models.
Technical corrections
- Line 93: CTM not defined
- Line 95: PA module not defined.
- I would suggest used “tropospheric ozone” instead of “ambient O3” when possible.
Citation: https://doi.org/10.5194/egusphere-2022-1271-RC1 -
AC1: 'Reply on RC1', Xuesong Wang, 17 Apr 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-1271/egusphere-2022-1271-AC1-supplement.pdf
-
RC2: 'Comment on egusphere-2022-1271', Anonymous Referee #2, 28 Jan 2023
Review Qu et al., 2022
Qu et al. present an analysis of the O3 budget in the ABL in two different ways: a concentration budget and a mass budget. They apply the budget calculations to the O3 budget over the Pearl River Delta based on simulations with WRF-CMAQ. The 2 different ways of calculating the O3 budget lead to opposing views on the main contributions to the O3 budget: while photochemistry dominates in the concentration budget, (vertical) transport dominates the mass budget. A tool is developed to calculate the budget contributions. A control simulation is performed, and in addition 3 brute force emission reduction scenarios are carried out. Budget calculation following the 2 methods are performed and the differences discussed.
Unfortunately, the way the paper is written makes it hard to judge its scientific merits, and I cannot recommend acceptation in its current form.
Major comments
- This is a dense paper without much guidance for the reader as to where you are going, which makes it hard to follow, and hard to judge the scientific merits of the work you describe. I had to reread it 3 times and still I am getting lost in the details. Please rewrite it in a more structured way, and indicate the purpose of each section in its first sentence. For instance, in section 2.6 a number of scenario runs seems to appear out of the blue. Where are the results of these runs used/discussed?
- What is actually lacking is an explanation of why 2 different budget methods give such different results. Is it mainly a boundary conditions problem? A change in mass does not lead to a change in concentration when the background concentration is similar over larger regions? Maybe it is discussed in L445-448?
Minor comments
L50 (and throughout MS): O3 processes --> O3-related processes
L74: pls rephrase sentence
L416: “High contributions of …” Unclear sentence. Please rephrase.
L461: what do you mean by ‘a longer time’?
Citation: https://doi.org/10.5194/egusphere-2022-1271-RC2 -
AC2: 'Reply on RC2', Xuesong Wang, 17 Apr 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-1271/egusphere-2022-1271-AC2-supplement.pdf
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
-
RC1: 'Comment on egusphere-2022-1271', Anonymous Referee #1, 19 Jan 2023
General Comments
- Understanding the processes controlling the O3 concentration in a specific area is important to design emission reduction strategies to reduce the harmful effects of tropospheric O3. This paper focuses on two processes that take place in the O3 cycle: transport and photochemistry.
- The paper discusses two methodological approaches to understand two O3 processes (transport and photochemistry) which are the O3 budget and the O3 source apportionment. Authors claims that there is a contradictory view on the role of transport and photochemistry in O3 pollution between the budget calculation studies and O3 source apportionment studies, because both studies provide different information. In my point of view, they are two different approaches difficult to compare, so it is normal they provide different results. However, as the authors show in the paper it is possible to learn from the both of them.
- I think the paper is organized in a way that it does not help to understand its objective and methodology, even it shows a hard work behind. So, in my opinion, this manuscript was hard to follow and understand, and consequently to review. Furthermore, it could help if authors improve the readability of the text. Overall, there are too many pronouns and missing nouns that make difficult to follow the main idea of some sentences. Authors should review the text carefully and provide a more accurate reference to key concepts, also being consistent in the way they do it along the manuscript.
I would suggest few clarifications and corrections:
Specific comments
- Abstract: difficult to get the important of the problem from the four first lines.
- The abstract does not help to understands the objective and the methodology approach. Ozone budget calculation and O3 source apportionment studies seems two different type of approaches difficult to compare, so it is normal the provide different results.
- Line 29: you mention two budgets, but you have not introduced them in the abstract. Is that related with the two type of studies?
- Line 74: the subject of that sentence “O3 source” does not make sence. Could your elaborate more the idea in that sentence.
- Line 88: “O3 source studies”. Use the same set of words to mention these studies. I guess in this case you want to say “O3 source apportionment studies”. The same comment in lines 90-91, “source apportionment studies” and “O3 budget studies”.
- Line 93: “CTM are capable of reproducing O3 processes”. In this sentence, you are attributing too much credibility to CTM, but models are not perfect and not always reproduce all the processes. I would be more realistic with what CTM can do, so I would suggest to rewrite this sentence.
- Line 220: “acceptable” from which point of view?
- Line 221: “reasonable” from which point of view?
- Lines 93-103 is specifically to CMAQ, it does not apply to any Eulerian CTMS (i.e. not CTM has a PA module).
- Line 121: “Horizontal transport through the borders of the PRD in four directions”. Is that correct? I guess you have two horizontal direction (x and y).
- Section 2.5 Model setup and validation. Even the model setup is described in the Qu et al. (2021) some basic details should be provided in the text, for example CMAQ and WRF version. Furthermore, the section is named “validation”. You mainly referenced Qu et al. (2021) but readers would appreciate a paragraph describing “why” we can trust on your modeling system’s results. The evaluation of ABL height with IAGOS measurements is very interesting. Could you elaborate more on the problems with CMAQ during the night?
- Line 236-237: Is that sentence well written?
- Source apportion method: Could you comment on the brute force disadvantages for O3 source apportionment calculation? Could CMAQ-ISAM source apportionment method improve your results?
- Conclusions: “This study concluded that transport and gas-phase chemistry play the main role in the O3 concentration and mass budgets”. Is it not new, right? Could you elaborate more this sentence as the main conclusion of this work.
- Conclusions: Could you elaborate more in the biases in your modelling results? For example, discussing the uncertainties in your emission data, meteorological fields, chemical and meteorological boundary conditions, chemistry in the models.
Technical corrections
- Line 93: CTM not defined
- Line 95: PA module not defined.
- I would suggest used “tropospheric ozone” instead of “ambient O3” when possible.
Citation: https://doi.org/10.5194/egusphere-2022-1271-RC1 -
AC1: 'Reply on RC1', Xuesong Wang, 17 Apr 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-1271/egusphere-2022-1271-AC1-supplement.pdf
-
RC2: 'Comment on egusphere-2022-1271', Anonymous Referee #2, 28 Jan 2023
Review Qu et al., 2022
Qu et al. present an analysis of the O3 budget in the ABL in two different ways: a concentration budget and a mass budget. They apply the budget calculations to the O3 budget over the Pearl River Delta based on simulations with WRF-CMAQ. The 2 different ways of calculating the O3 budget lead to opposing views on the main contributions to the O3 budget: while photochemistry dominates in the concentration budget, (vertical) transport dominates the mass budget. A tool is developed to calculate the budget contributions. A control simulation is performed, and in addition 3 brute force emission reduction scenarios are carried out. Budget calculation following the 2 methods are performed and the differences discussed.
Unfortunately, the way the paper is written makes it hard to judge its scientific merits, and I cannot recommend acceptation in its current form.
Major comments
- This is a dense paper without much guidance for the reader as to where you are going, which makes it hard to follow, and hard to judge the scientific merits of the work you describe. I had to reread it 3 times and still I am getting lost in the details. Please rewrite it in a more structured way, and indicate the purpose of each section in its first sentence. For instance, in section 2.6 a number of scenario runs seems to appear out of the blue. Where are the results of these runs used/discussed?
- What is actually lacking is an explanation of why 2 different budget methods give such different results. Is it mainly a boundary conditions problem? A change in mass does not lead to a change in concentration when the background concentration is similar over larger regions? Maybe it is discussed in L445-448?
Minor comments
L50 (and throughout MS): O3 processes --> O3-related processes
L74: pls rephrase sentence
L416: “High contributions of …” Unclear sentence. Please rephrase.
L461: what do you mean by ‘a longer time’?
Citation: https://doi.org/10.5194/egusphere-2022-1271-RC2 -
AC2: 'Reply on RC2', Xuesong Wang, 17 Apr 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2022/egusphere-2022-1271/egusphere-2022-1271-AC2-supplement.pdf
Peer review completion
AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Xuesong Wang on behalf of the Authors (17 Apr 2023)
Author's response
Author's tracked changes
Manuscript
ED: Referee Nomination & Report Request started (04 May 2023) by Andrea Pozzer
RR by Anonymous Referee #3 (16 May 2023)
ED: Reconsider after major revisions (22 May 2023) by Andrea Pozzer
AR by Xuesong Wang on behalf of the Authors (05 Jun 2023)
Author's response
Author's tracked changes
Manuscript
ED: Publish as is (13 Jun 2023) by Andrea Pozzer
AR by Xuesong Wang on behalf of the Authors (14 Jun 2023)
Manuscript
Journal article(s) based on this preprint
13 Jul 2023
Rethinking the role of transport and photochemistry in regional ozone pollution: insights from ozone concentration and mass budgets
Kun Qu, Xuesong Wang, Xuhui Cai, Yu Yan, Xipeng Jin, Mihalis Vrekoussis, Maria Kanakidou, Guy P. Brasseur, Jin Shen, Teng Xiao, Limin Zeng, and Yuanhang Zhang
Atmos. Chem. Phys., 23, 7653–7671, https://doi.org/10.5194/acp-23-7653-2023, https://doi.org/10.5194/acp-23-7653-2023, 2023
Short summary
Short summary
Basic understandings of ozone processes, especially transport and chemistry, are essential to support ozone pollution control, but studies often have different views on their relative importance. We developed a method to quantify their contributions in the ozone mass and concentration budgets based on the WRF-CMAQ model. Results in a polluted region highlight the differences between two budgets. For future studies, two budgets are both needed to fully understand the effects of ozone processes.
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State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
Laboratory for Modeling and Observation of the Earth System (LAMOS), Institute of Environmental Physics (IUP), University of Bremen, Bremen, Germany
Xuesong Wang
CORRESPONDING AUTHOR
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
Xuhui Cai
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
Yu Yan
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
Xipeng Jin
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
Mihalis Vrekoussis
Laboratory for Modeling and Observation of the Earth System (LAMOS), Institute of Environmental Physics (IUP), University of Bremen, Bremen, Germany
Center of Marine Environmental Sciences (MARUM), University of Bremen, Germany
Climate and Atmosphere Research Center (CARE-C), The Cyprus Institute, Cyprus
Jin Shen
State Key Laboratory of Regional Air Quality Monitoring, Guangdong Key Laboratory of Secondary Air Pollution Research, Guangdong Environmental Monitoring Center, Guangzhou 510308, China
Teng Xiao
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
Limin Zeng
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
Yuanhang Zhang
CORRESPONDING AUTHOR
State Key Joint Laboratory of Environmental Simulation and Pollution Control, College of Environmental Sciences and Engineering, Peking University, Beijing 100871, China
International Joint Laboratory for Regional Pollution Control, Ministry of Education, Beijing, 100816, China
Beijing Innovation Center for Engineering Science and Advanced Technology, Peking University, Beijing 100871, China
CAS Center for Excellence in Regional Atmospheric Environment, Chinese Academy of Sciences, Xiamen 361021, China
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Short summary
Basic understandings of ozone processes, especially transport and chemistry, are essential to reduce ozone pollution, but studies often have different views on their relative importance. To explore the causes, we developed a tool based on the WRF-CMAQ modelling results to quantify their contributions in the ozone mass and concentration budgets, and found that the difference between two budgets well explains these distinct views. Future studies should be careful with budget-type selections.
Basic understandings of ozone processes, especially transport and chemistry, are essential to...