the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 09 Oct 2023
Measurement report: Nocturnal subsidence behind the cold front enhances surface particulate matter in the plain regions: observation from the mobile multi-lidar system
Abstract. A multi-lidar system, mounted in vehicle to monitor the profiles of temperature, wind and particle optical properties, was utilized to investigate the winter fine particulate matter (PM2.5) pollution for a vertical perspective, in four cities in China in winter 2018. We observed the enhancement of surface nocturnal PM2.5 in two typical plain cities (Changzhou and Wangdu), which was attributed to the subsidence of PM2.5 transported from upstream polluted areas, with the wind turning north and downdrafts dominating. Combining with the observed surface PM2.5, the reanalysis meteorological data, and the GEOS-Chem model simulation, we revealed the Transport-Nocturnal PM2.5 Enhancement by Subsidence (T-NPES) events occurred frequently in the two cities, with percentages of 12.2 % and 18.0 %, respectively during Dec. 2018–Feb. 2019. Furthermore, the GEOS-Chem model simulation further confirmed that the ubiquity of winter T-NPES events in a large scale including North China Plain and Yangtze River Delta. Process analysis revealed that the subsidence was closely correlated with the southeasterly movement of the high-pressure system and the passage of the cold front, resulting in the increase of temperature aloft, a stronger inversion layer, and further PM2.5 accumulation in the atmospheric boundary layer. Thus, a conceptual model of the T-NPES events was proposed to highlight this surface PM2.5 enhancement mechanism in these plain regions. However, it was not applicable to the two cities in basin region (Xi’an and Chengdu), due to the obstruction of the weather system movement by the mountains surrounding the basin.
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Notice on discussion status
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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Preprint
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Supplement
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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.
- Preprint
(1461 KB) - Metadata XML
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Supplement
(1946 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-2178', Youngmin Noh, 26 Oct 2023
This paper installs a multi-lidar system that can measure aerosol extinction coefficient, wind direction, wind speed, and temperature on a vehicle and measures meteorological phenomena that can affect changes in PM2.5 concentration in real time in major cities in China. This is an analysis paper. Through analysis of observation results, the researchers revealed that T-NPES (Transport-Nocturnal PM2.5 Enhancement by Subsidence) is a relatively common and important pathway causing PM2.5 pollution in the surface layer of China's winter plains. It is believed that the above research results were possible thanks to the multi-lidar system. It is considered to be academically meaningful to reveal that T-NPES is the main cause of high concentration PM2.5. However, the main content of the paper is a simple structure that repeats the analysis of observation results, and no new results were found other than T-NPES. This is disappointing considering the long observation period and observation area.
Although this paper is judged to have low academic value to be published in this journal, it is ultimately judged that it can be published in this journal because it is a research result that can only be observed using a multi-lidar system.
However, it is judged that the minor parts below should be modified.
- It is deemed necessary to add essential information about the multi-lidar system.
- ex) In 3D visual scanning micro pulse lidar, information on measurement wavelength and lowest observable altitude must be added.
2. Figure 6 is difficult to read, so resolution, etc. needs to be improved.
Citation: https://doi.org/10.5194/egusphere-2023-2178-RC1 -
AC1: 'Reply on RC1', Haichao Wang, 14 Jan 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2178/egusphere-2023-2178-AC1-supplement.pdf
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RC2: 'Comment on egusphere-2023-2178', Anonymous Referee #2, 21 Dec 2023
This study reveal that the T-NPES is a relatively common and important pathway that causes PM2.5 pollution in the surface layer in the plain areas in winter China. Comprehensive mobile-lidar data and surface monitoring data are presented and analyzed to support the conclusion. The mechanism and potential regions of this phenomenon taking place is well demonstrated. Overall, the data presented herein is robust and the mechanism of T-NPES induced nocturnal PM2.5 increase is well explained. It is well suited to ACP journal and suggested to be published after addressing my following concerns.
- Line 43: A comma should be placed before ‘such as’ instead of a period.
- Figure 1(b): The label of black dots is suggested to be named as ‘route’.
- Section 2.1: In addition to the description of instruments used in this study, in terms of clarification, the method of data processing and QA/QC procedures should be at least briefly presented herein. And I suggest listing all parameters measured by lidar system and other surface station in a table with resolution, uncertainty and other related features for better readability.
- Line 332~334: What is the reason of the discrepancy between observed PM2.5 and simulated PM2.5 by geoschem? Can the model reproduce the same wind field and temperature as observed one which, as stated above in the manuscript, cause the subsidence of air mass aloft?
- Line 386: Please change ‘shirt’ to ‘shift’.
- Line 384~404: It seems like the type 4 T-NPES does not follow the same illustrated pattern as the other three and it is also different from the conceptual plot depicted in Fig 6. Maybe more information related to type 4 should be added into Fig 6.
- Although the authors presented several case studies to elaborately explain the pattern of T-NPES and its contribution on the increase of nocturnal surface PM2.5 concentrations, as stated in the text, the percentage of occurrence of this phenomenon was less than 20%. In that way, it comes to me that there should be some cases with increasing nocturnal PM2.5 in the surface during non-T-NPES condition, or with typical T-NPES event not causing increasing nocturnal PM2.5 in the surface. I suggest making some comparison among these three different cases, which might help to better illustrate the features and significance of T-NPES on PM2.5 pollution.
Citation: https://doi.org/10.5194/egusphere-2023-2178-RC2 -
AC2: 'Reply on RC2', Haichao Wang, 14 Jan 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2178/egusphere-2023-2178-AC2-supplement.pdf
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AC3: 'Reply on RC2', Haichao Wang, 14 Jan 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2178/egusphere-2023-2178-AC3-supplement.pdf
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-2178', Youngmin Noh, 26 Oct 2023
This paper installs a multi-lidar system that can measure aerosol extinction coefficient, wind direction, wind speed, and temperature on a vehicle and measures meteorological phenomena that can affect changes in PM2.5 concentration in real time in major cities in China. This is an analysis paper. Through analysis of observation results, the researchers revealed that T-NPES (Transport-Nocturnal PM2.5 Enhancement by Subsidence) is a relatively common and important pathway causing PM2.5 pollution in the surface layer of China's winter plains. It is believed that the above research results were possible thanks to the multi-lidar system. It is considered to be academically meaningful to reveal that T-NPES is the main cause of high concentration PM2.5. However, the main content of the paper is a simple structure that repeats the analysis of observation results, and no new results were found other than T-NPES. This is disappointing considering the long observation period and observation area.
Although this paper is judged to have low academic value to be published in this journal, it is ultimately judged that it can be published in this journal because it is a research result that can only be observed using a multi-lidar system.
However, it is judged that the minor parts below should be modified.
- It is deemed necessary to add essential information about the multi-lidar system.
- ex) In 3D visual scanning micro pulse lidar, information on measurement wavelength and lowest observable altitude must be added.
2. Figure 6 is difficult to read, so resolution, etc. needs to be improved.
Citation: https://doi.org/10.5194/egusphere-2023-2178-RC1 -
AC1: 'Reply on RC1', Haichao Wang, 14 Jan 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2178/egusphere-2023-2178-AC1-supplement.pdf
-
RC2: 'Comment on egusphere-2023-2178', Anonymous Referee #2, 21 Dec 2023
This study reveal that the T-NPES is a relatively common and important pathway that causes PM2.5 pollution in the surface layer in the plain areas in winter China. Comprehensive mobile-lidar data and surface monitoring data are presented and analyzed to support the conclusion. The mechanism and potential regions of this phenomenon taking place is well demonstrated. Overall, the data presented herein is robust and the mechanism of T-NPES induced nocturnal PM2.5 increase is well explained. It is well suited to ACP journal and suggested to be published after addressing my following concerns.
- Line 43: A comma should be placed before ‘such as’ instead of a period.
- Figure 1(b): The label of black dots is suggested to be named as ‘route’.
- Section 2.1: In addition to the description of instruments used in this study, in terms of clarification, the method of data processing and QA/QC procedures should be at least briefly presented herein. And I suggest listing all parameters measured by lidar system and other surface station in a table with resolution, uncertainty and other related features for better readability.
- Line 332~334: What is the reason of the discrepancy between observed PM2.5 and simulated PM2.5 by geoschem? Can the model reproduce the same wind field and temperature as observed one which, as stated above in the manuscript, cause the subsidence of air mass aloft?
- Line 386: Please change ‘shirt’ to ‘shift’.
- Line 384~404: It seems like the type 4 T-NPES does not follow the same illustrated pattern as the other three and it is also different from the conceptual plot depicted in Fig 6. Maybe more information related to type 4 should be added into Fig 6.
- Although the authors presented several case studies to elaborately explain the pattern of T-NPES and its contribution on the increase of nocturnal surface PM2.5 concentrations, as stated in the text, the percentage of occurrence of this phenomenon was less than 20%. In that way, it comes to me that there should be some cases with increasing nocturnal PM2.5 in the surface during non-T-NPES condition, or with typical T-NPES event not causing increasing nocturnal PM2.5 in the surface. I suggest making some comparison among these three different cases, which might help to better illustrate the features and significance of T-NPES on PM2.5 pollution.
Citation: https://doi.org/10.5194/egusphere-2023-2178-RC2 -
AC2: 'Reply on RC2', Haichao Wang, 14 Jan 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2178/egusphere-2023-2178-AC2-supplement.pdf
-
AC3: 'Reply on RC2', Haichao Wang, 14 Jan 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-2178/egusphere-2023-2178-AC3-supplement.pdf
Peer review completion
Journal article(s) based on this preprint
Data sets
Measurement report: Nocturnal subsidence behind the cold front enhances surface particulate matter in the plain regions: observation from the mobile multi-lidar system Yiming Wang, Haichao Wang, Shaojia Fan https://doi.org/10.5281/zenodo.8368944
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Yiming Wang
Haolin Wang
Yujie Qin
Xinqi Xu
Guowen He
Nanxi Liu
Shengjie Miao
Shaojia Fan
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1461 KB) - Metadata XML
-
Supplement
(1946 KB) - BibTeX
- EndNote
- Final revised paper