Synoptic Weather Patterns and Atmospheric Circulation Types of PM2.5 Pollution Periods in the Beijing-Tianjin-Hebei Region
, Shuai Wu, Luoqi Yang, Yincui Hu *, Bing Tian, Yan Yu *, Ning Ma, Pengsong Ji and Bo Zhang
Ramesh H. Kripalani
Leszek Kolendowicz
Round 1
Reviewer 1 Report
1. The authors have related the PM2.5 concentrations with synoptic weather patterns. They have identified specific patterns associated with PM2.5 concentrations which they designate as A-, N-, C-, NE- types.
2. Do you consider the topic original or relevant in the field? Does it address a specific gap in the field? Yes. Most of the recent studies focus on intra-seasonal or inter annual space-time scales. Very few studies are found on synoptic space-time scales. In fact with the advent of climate models, synoptic maps, main tool of a day-to-day earlier forecasters have gone out of fashion.
3. What does it add to the subject area compared with other published material? Yes, associating PM2.5 concentrations with specific atmospheric circulation types has added useful information.
4. What specific improvements should the authors consider regarding the methodology? What further controls should be considered? As suggested in my review the authors could add a figure (wind patterns) associated with each of the specific types (A-, NE- etc) the authors have identified.
The authors could add a figure showing the actual synoptic patterns / circulation types associated with the so-called A-type, N-type, NE-type and C-type. Also the PM2.5 Pollution patterns associated with these A, N, NE and C types. For clarification see Fog 4 and 5 in Singh etal (1978)
Singh SV, DA Mooley, RH Kripalani 1978: Synoptic Climatology of daily 700 mb summer monsoon flow patterns over India. Monthly Weather Review, 106, 510-525
5. Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed? Yes
6. Are the references appropriate? Yes
Author Response
To Reviewer 1
Thank you very much for your great efforts on our manuscript.
Comment 1: The authors have related the PM2.5 concentrations with synoptic weather patterns. They have identified specific patterns associated with PM2.5 concentrations which they designate as A-, N-, C-, NE- types.
Response: Thank you for your valuable advice. As Reviewer considered, in this paper, PM2.5 concentration monitoring PM2.5 data in BTH region during 2019-2022 and TAP data were performed significance test, and TAP data is applied to select a pollution period during study period. Lamb-Jenkinson objective classification method is applied to calculate the daily atmospheric circulation characteristics during study period. Atmospheric circulation characteristics were analyzed with circulation conditions and physical parameter fields during a pollution period, including the potential temperature field, humidity, wind field and atmospheric pressure field characteristics. The results of this study will further explore the accumulation and diffusion rules of atmospheric pollutants in different atmospheric circulation characteristics, provide data support for trans-regional comprehensive remediation of air pollution, the formulation of ecological compensation standards for air pollution, and provide research support for objective analysis and evaluation of air pollution control effects and policy formulation.
Comment 2: Do you consider the topic original or relevant in the field? Does it address a specific gap in the field? Yes. Most of the recent studies focus on intra-seasonal or inter annual space-time scales. Very few studies are found on synoptic space-time scales. In fact with the advent of climate models, synoptic maps, main tool of a day-to-day earlier forecasters have gone out of fashion.
Response: Thank you for your valuable advice. As Reviewer considered, the Lamb-Jenkinson objective classification method was used to study the changes of circulation classification at the beginning, middle and end of air pollution period. In addition, the influence of physical parameter field on weather conditions is also considered.
Comment 3: What does it add to the subject area compared with other published material? Yes, associating PM2.5 concentrations with specific atmospheric circulation types has added useful information.
Response: Thank you for your valuable advice. As Reviewer considered, we have optimized some of the descriptions to make it easier for readers to understand these useful information.
Comment 4: What specific improvements should the authors consider regarding the methodology? What further controls should be considered? As suggested in my review the authors could add a figure (wind patterns) associated with each of the specific types (A-, NE- etc) the authors have identified.
The authors could add a figure showing the actual synoptic patterns / circulation types associated with the so-called A-type, N-type, NE-type and C-type. Also the PM2.5 Pollution patterns associated with these A, N, NE and C types. For clarification see Fog 4 and 5 in Singh et al (1978) Singh SV, DA Mooley, RH Kripalani 1978: Synoptic Climatology of daily 700 mb summer monsoon flow patterns over India. Monthly Weather Review, 106, 510-525
Response: Thank you for your valuable advice. As Reviewer considered, we add Figure 5 to show the actual weather patterns of three major atmospheric circulations (A-type, N-type, and NE-type) during the pollution period, and illustrate the relationship with PM2.5 transport and accumulation in description. Furthermore, we also have made the amendment and marked in red.
Comment 5: Are the conclusions consistent with the evidence and arguments presented and do they address the main question posed? Yes
Response: Thank you for your valuable advice. As Reviewer considered, we optimized some of the descriptions.
Comment 6: Are the references appropriate? Yes
Response: Thank you for your valuable advice. As Reviewer considered, we optimized some of the references.
Reviewer 2 Report
The content of the manuscript is very interesting and the scientific comunity would gain a lot with this analysis. However, it must be improved. Firstly, an extensive editing of English language is required, mainly after section 3.3.
Secondly, the figures' legends (figures 5 to 7) should be corrected. (Are they really trends of just fields of the different variables?) - They could also be from the higher to the lower level. Synoptic meteorology symbols could also be drawn in the Figure (through, cold front).
Some concepts should be explained either in the introduction or in the results sections, such as: the importance of humidity (rainout and washout processes), and radiation (what is meant by "radiation range" in line 283, "humidity radiation" in line 321, and "radiation edge" in line 348?).
Notation of hPa should be corrected throughout the text.
An extensive editing of English language is required, mainly after section 3.3.
Author Response
To Reviewer 2
Thank you very much for your great efforts on our manuscript.
Comment 1: The content of the manuscript is very interesting and the scientific comunity would gain a lot with this analysis. However, it must be improved. Firstly, an extensive editing of English language is required, mainly after section 3.3.
Response: Thank you for your valuable advice. We are so sorry for the English language. As Reviewer considered, we have checked the text of the paper carefully and corrected the sentences with a professional assistance in writing. Furthermore, we have made the amendment.
Comment 2: Secondly, the figures' legends (figures 5 to 7) should be corrected. (Are they really trends of just fields of the different variables?) - They could also be from the higher to the lower level. Synoptic meteorology symbols could also be drawn in the Figure (through, cold front).
Response: Thank you for your valuable advice. We are so sorry for the unclear legends. As Reviewer considered, we have made the amendment of the figures. In Section 3.3, we add a paragraph start from description to summarize and describe the data results processed to show the change trend of different variables, which is convenient for readers to understand. Considering too many elements presented in Figure 6, Synoptic meteorology symbols driven by meteorological fields, including through, cold front and other descriptions, are added to Section 3.3 introduce. And we have made the amendment of the Section 3.3 and marked in red.
Comment 3: Some concepts should be explained either in the introduction or in the results sections, such as: the importance of humidity (rainout and washout processes), and radiation (what is meant by "radiation range" in line 283, "humidity radiation" in line 321, and "radiation edge" in line 348?).
Response: Thank you for your valuable advice. As Reviewer considered, the introduction of some concepts has been added in the paper, and some erroneous concepts have been corrected. And we have made the amendment and marked in red.
Comment 4: Notation of hPa should be corrected throughout the text.
Response: Thank you for your valuable advice. We have replaced notation of hPa by our previous work and marked in red.
Reviewer 3 Report
This is a very insightful article that delves into the flow of pollutants through different climate patterns.
Based on this article, I have two main questions:
First question: In lines 56-61, it is mentioned that domestic and foreign scholars have three methods for statistical classification of atmospheric circulation characteristics. The first method is subjective classification completed by researchers according to their professional knowledge and based on weather maps and meteorological principles. Due to researchers' subjectivity, there is no systematic method to test and verify the results, so this method has not been widely used. Is there any literature or systematic methods to prove the naming of these cyclones in meteorological classification that can be added?
Second question: Regarding Lamb-Jenkinson objective classification method, I think it is not easy to understand the introduction. In reference [33], the formula (1) is
u=1/2[p(12)+p(13)−p(4)−p(5)]
but in this article, the formula changed to
u=1/2[p(12)+p(13)+p(4)−p(5)]
can the author explain the formula? if it is wrong, please reconfirm the result.
Minor suggestion:
1. Formula (2) need to add ] at the end of the formula
2. Line 160 represent point A, A1, A2, is the A equal to type A? If not, please change to another name, it’s easy to confuse the reader.
Author Response
To Reviewer 3
Thank you very much for your great efforts on our manuscript.
Comment 1: In lines 56-61, it is mentioned that domestic and foreign scholars have three methods for statistical classification of atmospheric circulation characteristics. The first method is subjective classification completed by researchers according to their professional knowledge and based on weather maps and meteorological principles. Due to researchers' subjectivity, there is no systematic method to test and verify the results, so this method has not been widely used. Is there any literature or systematic methods to prove the naming of these cyclones in meteorological classification that can be added?
Response: Thank you for your valuable advice. As Reviewer considered, we can use literature or systematic methods to prove the naming of these cyclones in meteorological classification that can be added. As shown in the reference [1], Lamb uses professional knowledge and based on weather maps and meteorological principles, Six types of atmospheric circulation (AC-type, W-type, NW-type, N-type, E-type and S-type) over the British Isles during 1898-1947 were defined. The main criteria for the definition are meteorological features, including cold front, warm front, cyclone and anticyclone. The diurnal variation frequency of different types of weather patterns in a year is calculated and long time series is used to define the variation.
[1] Lamb H H . Types and spells of weather around the year in the British Isles : Annual trends, seasonal structure of the year, singularities[J]. Quarterly Journal of the Royal Meteorological Society, 2010, 76.
Comment 2: Regarding Lamb-Jenkinson objective classification method, I think it is not easy to understand the introduction. In reference [33], the formula (1) is
u=1/2[p(12)+p(13)−p(4)−p(5)]
but in this article, the formula changed to
u=1/2[p(12)+p(13)+p(4)−p(5)]
can the author explain the formula? if it is wrong, please reconfirm the result.
Response: Thank you for your valuable advice. We are so sorry for the formula. As Reviewer considered, we have checked all the formulas of the paper carefully and corrected the formulas. In addition, we add an introduction to the Lamb-Jenkinson objective classification method on description to facilitate the reader's understanding. Furthermore, we also have made the amendment and marked in red.
Comment 3: Formula (2) need to add ] at the end of the formula
Response: Thank you for your valuable advice. We are so sorry for the formula. As Reviewer considered, we have checked all the formulas of the paper carefully and corrected the formulas. Furthermore, we also have made the amendment and marked in red.
Comment 4: Line 160 represent point A, A1, A2, is the A equal to type A? If not, please change to another name, it’s easy to confuse the reader.
Response: Thank you for your valuable advice. As Reviewer considered, point A is not the same as A-type atmospheric circulation. The significant symbol have been replaced in the Figure 2 and description in the manuscript. Furthermore, we also have made the amendment and marked in red.
Reviewer 4 Report
The reviewed article entitled "Synoptic Weather Patterns and Atmospheric Circulation Types 2 of PM2.5 Pollution Periods in the Beijing-Tianjin-Hebei Region" concerns issues important from the point of view of environmental protection, in particular important for protection against PM 2.5 dust pollution.
The authors conducted a detailed analysis of atmospheric circulation in the research period 2019-2022 using the Lamb-Jenkinson objective classification method and tests of the selected period with the concentration of pollutants exceeding 100 micrograms per m3 in the period of January 2-4, 2019.
Considering the importance of the research problem in the situation of high air pollution with PM2.5 dust, the purpose of the research is justified. The authors used a very large set of data in order to characterize the course of pollutant concentrations in the analysed period, determine the type of atmospheric circulation and weather conditions. The research results obtained are interesting.
However, the reviewed article has some shortcomings.
Major remarks:
The authors should pay attention to explaining in the first part of the study how atmospheric circulation, as well as the temperature, humidity, and wind fields, affect the possibilities of dust dispersal and deposition. There is no such explanation in the study. There is also no explanation as to how the thermodynamic equilibrium of the atmosphere related to, for example, high-pressure systems, affects the possibility of deposition of pollutants or their longer retention in the suspended form in the air over a given area. This is one of the key elements in the analysis of the possibility of spreading and deposition of air pollutants.
A detailed description of the atmospheric circulation and the spatial distribution of air temperature values on January 2-4, 2019 should be supplemented with explanations related to the above-mentioned issues. This would give the reader a fuller insight into the actual causes of the high concentration of pollination in the analysed three-day period. The present analysis is incomplete. In addition, in the initial part of the study presenting the obtained research results, there should be comments regarding the explanation of changes in PM 2.5 concentrations during the year, with an indication of the heating season in the winter as one of the most important causes of higher pollution. Such a remark can be found, however in the final part of the work.
Minor remarks:
- row 43 abbreviation BTH should be explained,
- row 90-91 – information on the time period in which the threshold is exceeded should be added. I understand that this period applies to the day,
- chapter 2 - there is no map with the research area marked on the background of, for example, China or Asia,
- chapter 2.1.1 - no information from which period the meteorological data was downloaded,
- chapter 2.1.2 - lack of detailed information on how polluted periods were determined. There is no information on whether the concentration of 100 micrograms concerned the average daily value or whether these were hourly values. There is also no information in this chapter on the period from which the pollution data was used.
- Table 2 - the description of the table lacks information for which period the frequency of circulation types was calculated. There is no unit for frequency results (%?, number of days?). The obtained results lack circulation from the western and southern sectors. Is this normal in this geographic region?
- row 261-264 - on what basis do the authors believe that the type of circulation was beneficial for the accumulation of pollutants? The statement needs to be supplemented,
- row 282-283 - the sentence is not understandable,
- Figure 5 - in the description of the figure, it is better to use the term changes instead of trends,
- row 328-330 - lack of literature support for the formulated sentence,
- row 333-334 - lack of literature support for the formulated sentence,
- row 347-348 - the sentence is unclear,
- row 413-416 - the sentence is unclear.
Author Response
To Reviewer 4
Thank you very much for your great efforts on our manuscript.
Comment 1: The authors should pay attention to explaining in the first part of the study how atmospheric circulation, as well as the temperature, humidity, and wind fields, affect the possibilities of dust dispersal and deposition. There is no such explanation in the study. There is also no explanation as to how the thermodynamic equilibrium of the atmosphere related to, for example, high-pressure systems, affects the possibility of deposition of pollutants or their longer retention in the suspended form in the air over a given area. This is one of the key elements in the analysis of the possibility of spreading and deposition of air pollutants.
Response: Thank you for your valuable advice. As Reviewer considered, we have added descriptions of how atmospheric circulation, temperature, humidity, and wind fields affect the dispersion and deposition of pollutants in Section 1. The effect of atmospheric thermodynamics on pollutant deposition and suspension time is explained. Additionally, we attach corresponding references for support.
Comment 2: A detailed description of the atmospheric circulation and the spatial distribution of air temperature values on January 2-4, 2019 should be supplemented with explanations related to the above-mentioned issues. This would give the reader a fuller insight into the actual causes of the high concentration of pollination in the analyzed three-day period. The present analysis is incomplete. In addition, in the initial part of the study presenting the obtained research results, there should be comments regarding the explanation of changes in PM 2.5 concentrations during the year, with an indication of the heating season in the winter as one of the most important causes of higher pollution. Such a remark can be found, however in the final part of the work.
Response: Thank you for your valuable advice. As Reviewer considered, we add description of the atmospheric circulation and the spatial distribution of air temperature values on January 2-4, 2019 in Section 3.3. Additionally, we added the winter heating season as a cause of increased pollution at the beginning of the study. Furthermore, we also have made the amendment and marked in red.
Comment 3:
- row 43 abbreviation BTH should be explained,
- row 90-91 – information on the time period in which the threshold is exceeded should be added. I understand that this period applies to the day,
- chapter 2 - there is no map with the research area marked on the background of, for example, China or Asia,
- chapter 2.1.1 - no information from which period the meteorological data was downloaded,
- chapter 2.1.2 - lack of detailed information on how polluted periods were determined. There is no information on whether the concentration of 100 micrograms concerned the average daily value or whether these were hourly values. There is also no information in this chapter on the period from which the pollution data was used.
- Table 2 - the description of the table lacks information for which period the frequency of circulation types was calculated. There is no unit for frequency results (%?, number of days?). The obtained results lack circulation from the western and southern sectors. Is this normal in this geographic region?
- row 261-264 - on what basis do the authors believe that the type of circulation was beneficial for the accumulation of pollutants? The statement needs to be supplemented,
- row 282-283 - the sentence is not understandable,
- Figure 5 - in the description of the figure, it is better to use the term changes instead of trends,
- row 328-330 - lack of literature support for the formulated sentence,
- row 333-334 - lack of literature support for the formulated sentence,
- row 347-348 - the sentence is unclear,
- row 413-416 - the sentence is unclear.
Response: Thank you for your valuable advice. As Reviewer considered, we have completed the explanation of abbreviations, modified unclear sentences, and added corresponding formula sentence literature support. Additionally, we add background markers in Figure 1, frequency result units in Table 2, meteorological data download period and criteria for determining pollution period. We have details of how to determine the pollution period described in Section 1. Furthermore, we also have made the amendment and marked in red.
Round 2
Reviewer 3 Report
I think this paper can be published
Reviewer 4 Report
The authors took into account the reviewer's comments and made appropriate changes to the text of the article. In my opinion, the article can be published in its current form.
