Distinct effects of Fine and Coarse Aerosols on Microphysical Processes of Shallow Precipitation Systems in Summer over Southern China

Chen, Fengjiao; Yang, Yuanjian; Yu, Lu; Li, Yang; Liu, Weiguang; Liu, Yan; Lolli, Simone

doi:https://doi.org/10.5194/egusphere-2024-2206

Preprints

https://doi.org/10.5194/egusphere-2024-2206

Preprints

14 Aug 2024

| 14 Aug 2024

Distinct effects of Fine and Coarse Aerosols on Microphysical Processes of Shallow Precipitation Systems in Summer over Southern China

Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli

Abstract. The densely populated South China, adjacent to the South China Sea, which is associated with shallow precipitation during summer, makes it a natural experimental region for studying the impact of aerosols on shallow precipitation events. Using 8 years of GPM DPR, MERRA-2 aerosol, and ERA reanalysis data, this study investigates the potential influence of coarse and fine aerosol modes on the precipitation structure and microphysical processes of shallow precipitation in South China. Statistical results indicate that during coarse aerosol-polluted conditions, shallow precipitation clouds have a lower median Storm Top Height (STH, ~3.2 km), but a higher mean near-surface rainfall (RR, ~1.78 mm h^-1), characterized by high concentrations of large raindrops, mainly driven by significant collision-coalescence processes (accounting for 74.1 %). Conversely, during fine aerosol-polluted conditions, shallow precipitation clouds develop deeper median STH ~3.7 km with lower surface RR characterized by a low concentration of small hydrometeors, resulting from increased breakup processes (33.1 %) and reduced collision-coalescence processes (69.6 %). The coarse (fine) aerosols act as promoters (inhibitors) of the radar and radar reflectivity in the profile of shallow precipitation, regardless of dynamic and humid conditions. The effect of coarse aerosols in promoting precipitation and the inhibiting effect of fine aerosols are the most significant under low humidity conditions, mainly attributed to the significantly enhanced collision-coalescence processes, exceeding 22.2 %. Furthermore, the increase in RR above 3 km during coarse aerosol-polluted environments is mainly driven by the high concentration of hydrometeors in low instability conditions, while by large hydrometeors in high instability environments.

Received: 15 Jul 2024 – Discussion started: 14 Aug 2024

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Journal article(s) based on this preprint

04 Feb 2025

Distinct effects of fine and coarse aerosols on microphysical processes of shallow-precipitation systems in summer over southern China

Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli

Atmos. Chem. Phys., 25, 1587–1601, https://doi.org/10.5194/acp-25-1587-2025,https://doi.org/10.5194/acp-25-1587-2025, 2025

Short summary

Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli

Interactive discussion

Status: closed

CC1:
'Comment on egusphere-2024-2206', Xiong Hu, 29 Aug 2024

The sample selection method for aerosol-type-dominated pollution seems to be incorrect, which will produce overlapping samples. For example, the number of samples that meet both FA and CSA greater than the threshold is small but still exists. The AOD value of FA is generally greater than that of CSA. How can this mean that CSA is the main influence in the Polluted_Coarse type defined in the article? It is not ruled out that the AOD value of FA is also large at the same time.
In addition, when describing the samples, there are multiple values in the text that are inconsistent with the description in Table 1—for example, lines 196 and 204.

Citation: https://doi.org/10.5194/egusphere-2024-2206-CC1
- AC3: 'Reply on CC1', Yuanjian Yang, 26 Oct 2024
  
  Dear Reviewer and Editors:
  
  We are sincerely grateful to the editor and reviewer for their valuable time for reviewing our manuscript. The comments are very helpful and valuable, and we have addressed the issues raised by the reviewer in the revised manuscript. Please find our point-by-point response (in blue text) to the comments (in black text) raised by the reviewer. We have revised the paper according to your comments (highlighted in blue text of the revised manuscript).
  
  Sincerely yours,
  
  Dr. Yuanjian Yang, representing all co-authors
  
  Citation: https://doi.org/10.5194/egusphere-2024-2206-AC3
RC1:
'Comment on egusphere-2024-2206', Anonymous Referee #1, 05 Sep 2024

The manuscript presents a comprehensive analysis of how different aerosol types affect the microphysical properties and precipitation patterns of shallow precipitation systems in South China. Utilizing a comprehensive dataset that includes GPM DPR data, MERRA-2, and ERA5, the study finds that coarse aerosols generally enhance rainfall by promoting collision-coalescence processes, leading to larger raindrop sizes and higher rainfall rates. In contrast, fine aerosols tend to suppress rainfall through increased raindrop breakup and reduced coalescence efficiency. The study's findings are particularly relevant for understanding regional precipitation patterns and aerosol-cloud-precipitation interactions. Overall, this manuscript is well-organized and of clear scientific significance. I want to offer the following minor suggestions:
1. The MERRA-2 aerosol data product may have certain uncertainties in its representation of aerosol species and concentrations. It would be beneficial to include a brief introduction to the known limitations of the MERRA-2 product, as well as acknowledging the potential impacts of these uncertainties.
2. The different datasets, including GPM DPR data, MERRA-2, and ERA5, have different spatial resolutions, which might not fully capture the fine-scale processes in aerosol-cloud interactions. The authors may discuss the consistency of different products to strengthen the conclusions.
3. The study focuses primarily on the microphysical processes within shallow precipitation systems. The authors may discuss whether it is possible to extend the approach from shallow to deep convection or mixed-phase cloud regime.
4. The authors may clarify the methodology for aerosol classification, particularly the choice of thresholds for defining polluted and clean environments. Is it possible to have some sensitive test for the threshold to ensure the representation of the conclusions?
5. In addition to the CAPE, the authors may acknowledge the contribution of other meteorological factors, as well as their potential role in affecting aerosol-precipitation relationships.

Citation: https://doi.org/10.5194/egusphere-2024-2206-RC1
- AC1: 'Reply on RC1', Yuanjian Yang, 26 Oct 2024
  
  Dear Reviewer and Editors:
  We are sincerely grateful to the editor and reviewer for their valuable time for reviewing our manuscript. The comments are very helpful and valuable, and we have addressed the issues raised by the reviewer in the revised manuscript. Please find our point-by-point response (in blue text) to the comments (in black text) raised by the reviewer. We have revised the paper according to your comments (highlighted in blue text of the revised manuscript).
  
  Sincerely yours,
  Dr. Yuanjian Yang, representing all co-authors
  
  Citation: https://doi.org/10.5194/egusphere-2024-2206-AC1
RC2:
'Comment on egusphere-2024-2206', Anonymous Referee #2, 14 Sep 2024
This present study the potential effects of different types of aerosols on precipitation maicrophyscis. Many previous studies have revealed the potential effect of aerosols on precipitation, while little attention has been paid on the aerosols on precipitation microphysical strucutres and processes, considering the different aerosol species. This topic is interesting and meaningful. The paper is composed logically, well-written, and the figures are clear. How I have some concerns of the manuscript, therefore a major revision is suggested.

Major suggestions
Why choose specific criteria for defining aerosols and identifying polluted environments? Are there any references to support this choice? Could different criteria lead to varying conclusions about the results?

This study primarily outlines the main observational findings and potential underlying mechanisms of aerosols on precipitation. How do these findings compare with previous studies? Please include more comparisons with past research, highlighting both differences and similarities.

Minor suggestions
Line 30, radar and radar reflectivity … -> radar reflectivity

Line 34-35, where does the “22.2% “ come from?

Line 73, Other studies suggest -> Another study suggests

Line 138, This sentence is missing a period.

Line 91, efficiency of coalescence of rain droplets-> coalescence efficiency of rain droplets

Lines 96 – 97 , for the study on the effect of the effect of aerosols on shallow precipitation -> the study of aerosols effect on shallow precipitation.

Lines 173-176, Is there any reference for the definitations for the fine and coarse aerosols?

Line 204, it should be 8967.

Line 226, how about the ratios of dust and sea salt aerosols to the coarse aerosol? Simimliar, how about the black carbon, organic carbon and sulfate to the fine aerosols?

Line 227, “Coarse AOD > 0.0425” is duplicated.

Line 240, “promoting” -> benifical for the

Line 245, “mode” - > environments

Line 251, provide some reference to support this statement.

Line 281, not in italics.

Line 359, fine mode -> fine ; similarly in Line 367

In section 3.3, since precipitation can be affected by many other effects, please explain more about the reasons of choosing these two factors (CAPE and RH at 850hPa).

Line 502, where the -> the

Line 550, modify the pharase “the presence of CAPE and RH”

Line 554, notify the previous findings specifically.

Line 639: available on May 2023 -> accessed in May 2023
Citation: https://doi.org/10.5194/egusphere-2024-2206-RC2
- AC2: 'Reply on RC2', Yuanjian Yang, 26 Oct 2024
  
  Dear Reviewer and Editors:
  
  We are sincerely grateful to the editor and reviewer for their valuable time for reviewing our manuscript. The comments are very helpful and valuable, and we have addressed the issues raised by the reviewer in the revised manuscript. Please find our point-by-point response (in blue text) to the comments (in black text) raised by the reviewer. We have revised the paper according to your comments (highlighted in blue text of the revised manuscript).
  
  Sincerely yours,
  
  Dr. Yuanjian Yang, representing all co-authors
  
  Citation: https://doi.org/10.5194/egusphere-2024-2206-AC2

Interactive discussion

Status: closed

CC1:
'Comment on egusphere-2024-2206', Xiong Hu, 29 Aug 2024

The sample selection method for aerosol-type-dominated pollution seems to be incorrect, which will produce overlapping samples. For example, the number of samples that meet both FA and CSA greater than the threshold is small but still exists. The AOD value of FA is generally greater than that of CSA. How can this mean that CSA is the main influence in the Polluted_Coarse type defined in the article? It is not ruled out that the AOD value of FA is also large at the same time.
In addition, when describing the samples, there are multiple values in the text that are inconsistent with the description in Table 1—for example, lines 196 and 204.

Citation: https://doi.org/10.5194/egusphere-2024-2206-CC1
- AC3: 'Reply on CC1', Yuanjian Yang, 26 Oct 2024
  
  Dear Reviewer and Editors:
  
  We are sincerely grateful to the editor and reviewer for their valuable time for reviewing our manuscript. The comments are very helpful and valuable, and we have addressed the issues raised by the reviewer in the revised manuscript. Please find our point-by-point response (in blue text) to the comments (in black text) raised by the reviewer. We have revised the paper according to your comments (highlighted in blue text of the revised manuscript).
  
  Sincerely yours,
  
  Dr. Yuanjian Yang, representing all co-authors
  
  Citation: https://doi.org/10.5194/egusphere-2024-2206-AC3
RC1:
'Comment on egusphere-2024-2206', Anonymous Referee #1, 05 Sep 2024

The manuscript presents a comprehensive analysis of how different aerosol types affect the microphysical properties and precipitation patterns of shallow precipitation systems in South China. Utilizing a comprehensive dataset that includes GPM DPR data, MERRA-2, and ERA5, the study finds that coarse aerosols generally enhance rainfall by promoting collision-coalescence processes, leading to larger raindrop sizes and higher rainfall rates. In contrast, fine aerosols tend to suppress rainfall through increased raindrop breakup and reduced coalescence efficiency. The study's findings are particularly relevant for understanding regional precipitation patterns and aerosol-cloud-precipitation interactions. Overall, this manuscript is well-organized and of clear scientific significance. I want to offer the following minor suggestions:
1. The MERRA-2 aerosol data product may have certain uncertainties in its representation of aerosol species and concentrations. It would be beneficial to include a brief introduction to the known limitations of the MERRA-2 product, as well as acknowledging the potential impacts of these uncertainties.
2. The different datasets, including GPM DPR data, MERRA-2, and ERA5, have different spatial resolutions, which might not fully capture the fine-scale processes in aerosol-cloud interactions. The authors may discuss the consistency of different products to strengthen the conclusions.
3. The study focuses primarily on the microphysical processes within shallow precipitation systems. The authors may discuss whether it is possible to extend the approach from shallow to deep convection or mixed-phase cloud regime.
4. The authors may clarify the methodology for aerosol classification, particularly the choice of thresholds for defining polluted and clean environments. Is it possible to have some sensitive test for the threshold to ensure the representation of the conclusions?
5. In addition to the CAPE, the authors may acknowledge the contribution of other meteorological factors, as well as their potential role in affecting aerosol-precipitation relationships.

Citation: https://doi.org/10.5194/egusphere-2024-2206-RC1
- AC1: 'Reply on RC1', Yuanjian Yang, 26 Oct 2024
  
  Dear Reviewer and Editors:
  We are sincerely grateful to the editor and reviewer for their valuable time for reviewing our manuscript. The comments are very helpful and valuable, and we have addressed the issues raised by the reviewer in the revised manuscript. Please find our point-by-point response (in blue text) to the comments (in black text) raised by the reviewer. We have revised the paper according to your comments (highlighted in blue text of the revised manuscript).
  
  Sincerely yours,
  Dr. Yuanjian Yang, representing all co-authors
  
  Citation: https://doi.org/10.5194/egusphere-2024-2206-AC1
RC2:
'Comment on egusphere-2024-2206', Anonymous Referee #2, 14 Sep 2024
This present study the potential effects of different types of aerosols on precipitation maicrophyscis. Many previous studies have revealed the potential effect of aerosols on precipitation, while little attention has been paid on the aerosols on precipitation microphysical strucutres and processes, considering the different aerosol species. This topic is interesting and meaningful. The paper is composed logically, well-written, and the figures are clear. How I have some concerns of the manuscript, therefore a major revision is suggested.

Major suggestions
Why choose specific criteria for defining aerosols and identifying polluted environments? Are there any references to support this choice? Could different criteria lead to varying conclusions about the results?

This study primarily outlines the main observational findings and potential underlying mechanisms of aerosols on precipitation. How do these findings compare with previous studies? Please include more comparisons with past research, highlighting both differences and similarities.

Minor suggestions
Line 30, radar and radar reflectivity … -> radar reflectivity

Line 34-35, where does the “22.2% “ come from?

Line 73, Other studies suggest -> Another study suggests

Line 138, This sentence is missing a period.

Line 91, efficiency of coalescence of rain droplets-> coalescence efficiency of rain droplets

Lines 96 – 97 , for the study on the effect of the effect of aerosols on shallow precipitation -> the study of aerosols effect on shallow precipitation.

Lines 173-176, Is there any reference for the definitations for the fine and coarse aerosols?

Line 204, it should be 8967.

Line 226, how about the ratios of dust and sea salt aerosols to the coarse aerosol? Simimliar, how about the black carbon, organic carbon and sulfate to the fine aerosols?

Line 227, “Coarse AOD > 0.0425” is duplicated.

Line 240, “promoting” -> benifical for the

Line 245, “mode” - > environments

Line 251, provide some reference to support this statement.

Line 281, not in italics.

Line 359, fine mode -> fine ; similarly in Line 367

In section 3.3, since precipitation can be affected by many other effects, please explain more about the reasons of choosing these two factors (CAPE and RH at 850hPa).

Line 502, where the -> the

Line 550, modify the pharase “the presence of CAPE and RH”

Line 554, notify the previous findings specifically.

Line 639: available on May 2023 -> accessed in May 2023
Citation: https://doi.org/10.5194/egusphere-2024-2206-RC2
- AC2: 'Reply on RC2', Yuanjian Yang, 26 Oct 2024
  
  Dear Reviewer and Editors:
  
  We are sincerely grateful to the editor and reviewer for their valuable time for reviewing our manuscript. The comments are very helpful and valuable, and we have addressed the issues raised by the reviewer in the revised manuscript. Please find our point-by-point response (in blue text) to the comments (in black text) raised by the reviewer. We have revised the paper according to your comments (highlighted in blue text of the revised manuscript).
  
  Sincerely yours,
  
  Dr. Yuanjian Yang, representing all co-authors
  
  Citation: https://doi.org/10.5194/egusphere-2024-2206-AC2

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload

AR by Yuanjian Yang on behalf of the Authors (26 Oct 2024) Author's response Author's tracked changes Manuscript

ED: Referee Nomination & Report Request started (06 Nov 2024) by Luis A. Ladino

RR by Anonymous Referee #2 (18 Nov 2024)

RR by Anonymous Referee #1 (24 Nov 2024)

ED: Publish subject to minor revisions (review by editor) (25 Nov 2024) by Luis A. Ladino

I thank the authors for properly addressing the comments and suggestions raised by the different referees. However, I encourage the authors to take into account the following comments before the manuscript is accepted for its publication.

Minor comments:
1. The authors used “aerosols” and “aerosol” along the manuscript to refer to "aerosol particles". Given that the gas phase of the aerosols are not taken into account in this study, I suggest changing “aerosols” and “aerosol” by “aerosol particle or particles” along the manuscript.
2. Droplets and raindrops are not particles. Please fix this.
3. The usage of hydrometeor and hydrometeors along the text is not always correct. I suggest referring to raindrops, cloud drops or the correct hydrometeor and avoid using hydrometeor(s).
4. Figure 6. It is necessary to indicate the meaning of each color
5. Figure 7. It is necessary to indicate the meaning of each color
6. Figure 10. The figure caption is incorrect. Please fix it.

Technical comments:
Lines 20: Please define GPM, DPR, MERRA-2, and ERA
Line 49: What do the authors mean with the “marine continent”
Lines 88-89: I suggest replacing “most regions of eastern China (except Northeast China) (Sun et al., 2022); Xiao et al. (2022)” by “most regions of eastern China (Sun et al., 2022), except Northeast China as Xiao et al. (2022) found”
Line 124: Replace “observations from Aerosol” by “observations from the Aerosol”
Line 125: Replace “products from Advanced” by “products from the Advanced”
Line 128: Define “AOD”
Line 141: Replace “In this present” by “In the present”
Line 151: Define “2ADPR”
Line 151: Replace “and the generalized intercept Nw (in mm-1 m-3)” by “and the generalized intercept Nw (i.e., number concentration of droplets in mm-1 m-3 )”
Line 159: Replace “in vertically” by “in vertical”
Lines 162-163: Replace “and STH below 5 km in altitude. The storm top height (STH) is” by “and the storm top height (STH) below 5 km in altitude. The STH is”
L192: Replace “occurrence of the shallow” by “occurrence of a shallow”
Line 243: Replace “aerosols before the shallow” by “aerosols before a shallow”
Line 270: Replace “number concentration of droplets (Nw) at” by “Nw at” as this was defined above.
Line 271: Replace “and mass-weighted mean diameter (Dm) at” by “and Dm at” as this was defined above.
Line 281: “other microphysical processes”. Please indicate the processes the authors are referring to.
Lines 284-285: “cloud microphysics, precipitation microphysics, and precipitation”. What is the difference between the three?
Line 297 and along the text: “small particles” and “large particles”. I think this should be “small droplets” and “large droplets”. Please revise the ms accordingly.
Lines 315-316: Replace “fine (b) aerosol-polluted and coarse (c) aerosol-” by “fine (b) and coarse (c) aerosol-”
Lines 348-350: This was already mentioned in Lines 338-340
Line 377 and along the text: Replace “of raindrop particles” by “of raindrops”
Line 379 and along the text: Replace “coalescence of hydrometeors dominates” by “coalescence of raindrops dominates”
Lines 385-386: The following is unclear “Similarly, the proportion of the hydrometeor particle breakup process is 33.1% (a decrease of 10%).”
Line 389: Replace “raindrop hydrometeors” by “raindrop”. Note that a raindrop is a hydrometeor, therefore, this sounds redundant.
Lines 483-484: Replace “maximum in aerosol coarse mode environments polluted” by “maximum in environments polluted”
Line 604: “higher concentrations” of what?
Lines 605-606: Replace “and larger raindrop sizes (average Dm = 1.24 mm) of hydrometeor particles.” By “and larger raindrops (average Dm = 1.24 mm)”
Line 608: “raindrop particles through microphysical processes such as condensation”. Do the authors mean collision- coalescence? Condensation is an effective process up to sizes ca. 20-30 um. Therefore, at the large drop sizes used in the present study condensation may not be of high importance.

Hide

AR by Yuanjian Yang on behalf of the Authors (29 Nov 2024) Author's response Author's tracked changes Manuscript

ED: Publish as is (29 Nov 2024) by Luis A. Ladino

AR by Yuanjian Yang on behalf of the Authors (01 Dec 2024) Manuscript

Journal article(s) based on this preprint

04 Feb 2025

Distinct effects of fine and coarse aerosols on microphysical processes of shallow-precipitation systems in summer over southern China

Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli

Atmos. Chem. Phys., 25, 1587–1601, https://doi.org/10.5194/acp-25-1587-2025,https://doi.org/10.5194/acp-25-1587-2025, 2025

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Fengjiao Chen, Yuanjian Yang, Lu Yu, Yang Li, Weiguang Liu, Yan Liu, and Simone Lolli

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The precipitation microphysical mechanisms responsible for the varied impacts of aerosols on shallow precipitation remain unclear. This study reveals that coarse aerosols invigorate shallow rainfall through enhanced coalescence processes, whereas fine aerosols suppress shallow rainfall via intensified breakup microphysical processes. These impacts are independent of thermodynamic environments but are more significant in low-humidity conditions.


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Distinct effects of Fine and Coarse Aerosols on Microphysical Processes of Shallow Precipitation Systems in Summer over Southern China

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Interactive discussion

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Journal article(s) based on this preprint

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