the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Significant Influence of UV-vis Irradiation on Cloud Activation Efficiencies of Ammonium Sulfate Aerosols under Simulated Chamber Conditions
Abstract. In this work, an optimized protocol to generate an expansion-type liquid clouds with and without UV-visible light irradiation conditions for simulation chamber studies is presented. Sensitivity of the process to key parameters such as initial relative humidities, temperature inhomogeneities, droplets lifetime or seed particle number is illustrated. The obtained clouds have shown that not all seeds particles were always activated and so an iterative numerical method has been re-designed to separate cloud droplets from non-activated seed particles during data analysis allowing the characterization of the cloud droplet formation properties without CCN counter data.
Two types of experiments, clouds without irradiation (N-IC) and under UV-visible light irradiation conditions (IC), have been conducted in the CESAM multiphase atmospheric chamber. Measured cloud droplet lifetimes were in good agreement with atmospheric droplet lifetimes. The achieved supersaturation in the cloud was mostly sensitive to the initial relative humidity in the chamber. The comparison between the cloud formation pattern of N-IC and LC was also investigated. Under illumination conditions, the generated clouds clearly showed a gradual activation of seed particles into droplets and thus of the microphysical properties like LWC and droplet concentration, while under dark conditions, clouds faced a flash activation of seed particles. Because this phenomenon may also impact the air/water partitioning of semi-volatile compounds, and it should be considered for further studies, especially in further multiphase photochemical studies implying water-soluble volatile organic compounds in the CESAM chamber.
- Preprint
(1819 KB) - Metadata XML
-
Supplement
(654 KB) - BibTeX
- EndNote
Status: closed (peer review stopped)
-
CC1: 'Comment on amt-2023-206', Harry ten Brink, 15 Mar 2024
-I would like to mention the omission in the list of chamber of the large flow-thru cloud chamber at ECN Petten with extensive performance tests (Khlystov et al. plus PhD thesis)
-The source of the UV radiation is not provided and apparently also heat in the form of IR radiation is provided by the source: this is as indicated absorbed by the water droplets
Are there data on the heat flux so that the heating can indeed be estimated?
Citation: https://doi.org/10.5194/amt-2023-206-CC1 -
CC2: 'Reply on CC1', Jean-Francois Doussin, 22 Mar 2024
Thank you very much for your interest to our paper and for letting us know.
Indeed our cloud chamber quick overview was more focused on static chambers rather than flow chambers for a better comparison with the CESAM facilty but we will pay attention to mention Petten facility in the final version.
Concerning light source and its UV/IR content : Indeed, it is not described in this paper as it has been largely described and commented in previous CESAM papers (including the original description by Wang et al, 2011). We may consider to add it as supplementary information in the final version if it is considered needed.
Again thank you for helping us to improve the paper
Citation: https://doi.org/10.5194/amt-2023-206-CC2 -
CC3: 'Reply on CC2', Harry ten Brink, 22 Mar 2024
I suggest to provide brief summary of the UV source plus a comment that it also emits heat radation (IR?) as now given as reason for a different nucleation regime later on
Citation: https://doi.org/10.5194/amt-2023-206-CC3
-
CC3: 'Reply on CC2', Harry ten Brink, 22 Mar 2024
-
CC2: 'Reply on CC1', Jean-Francois Doussin, 22 Mar 2024
-
RC1: 'Comment on amt-2023-206', Anonymous Referee #1, 27 Mar 2024
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2023-206/amt-2023-206-RC1-supplement.pdf
-
RC2: 'Comment on amt-2023-206', Anonymous Referee #3, 02 May 2024
Mandariya et al. present a protocol for generating quasi-adiabatic expansion clouds in the CESAM chamber under irradiated and non-irradiated conditions. Further, they present six experiments, three under irradiated and three under non-irradiated conditions. Overall, the manuscript fails to provide sufficient evidence for the influence of irradiation during cloud activation. The manuscript is not well written and needs major improvements in its grammar, sentence structure, and overall wording. I strongly recommend that the authors perform a full editorial review before re-submission. All in all, I cannot recommend publication of the manuscript in its current form in AMT.
Major comments
The authors perform a series of experiments using their newly designed protocol in order to identify the influence of UV-cis irradiation on cloud activation. However, experimental characteristics that the authors them self label to be important for cloud activation (RH, dew point T, dP, dT, initial number concentration), differ significantly between all experiments. The authors fail to provide sufficient evidence that the difference in cloud activation is caused by irradiation rather than the difference in these characteristics. A detailed uncertainty analysis on the influence of these different characteristics needs to be provided.The authors frequently point out that the chamber is affected by inhomogeneities (e.g., humidity, temperature) and turbulences. Due to the influence of these parameters on cloud activation, it is questionable if the CESAM chamber is an optimal choice for these experiments. A detailed characterization of these turbulences and inhomogeneities is required to identify their influence on cloud activation.
Specific comments
Line 42-44: Is there a more recent estimate on the re-evaporation of clouds? Do you have an estimate how often a CCN might be processed by multiple clouds?
Line 92: What does the abbreviation CESAM stand for?
Figure 3: Is this figure really necessary, considering that you provide similar figures later on?
Line 138: A background particle number concentration of 100 cm-3 is high. What impact do you expect this value has on cloud activation in CESAM?
Line 281-294: I recommend to first discuss the different experiments performed and than discuss a typical cloud run. Please provide a proper statement here on the intend of these experiments.
Line 306: Can you speculate on the reason behind this temperature increase? What influence has this on your conclusions?
Line 307-308: Why is this process not automated?
Table 1: What influence do you expect form the fundamentally different change in pressure for run IC-1, IC-2, and IC-3?
Line 354: You state that turbulent mixing and inhomogeneity affect the cloud evolution. Please provide an average mixing time of the chamber used.
Line 369-370: Can you comment on the impact of this assumption on your analysis?
Line 440-444: Again, please comment on the average chamber mixing time.
Line 493: Please provide the irradiation spectrum.Some technical corrections:
1st sentence: "an" is singular and refers to "clouds" plural. "droplets lifetime" should be "droplet lifetimes". "seeds particles" should be "seed particles".
Line 21: CCN is not defined
LIne 27: is "LC" supposed to be "IC"?
LIne 28: LWC is not defined
Line 30: "air/water partitioning of semi-volatile compounds, and it should be" the wording is awkward
Figure 1: In the text you mention that only one fan is used. In the figure, however, it looks as if there is a second fan slightly shaded. This is only shown if I open the pdf via a pdf-reader. If opened in the browser, it is not visible.
Figure 2: There are some artifacts in the figure. Like shadowed axis-labels etc. Again only visible when using a pdf-reader.Citation: https://doi.org/10.5194/amt-2023-206-RC2
Status: closed (peer review stopped)
-
CC1: 'Comment on amt-2023-206', Harry ten Brink, 15 Mar 2024
-I would like to mention the omission in the list of chamber of the large flow-thru cloud chamber at ECN Petten with extensive performance tests (Khlystov et al. plus PhD thesis)
-The source of the UV radiation is not provided and apparently also heat in the form of IR radiation is provided by the source: this is as indicated absorbed by the water droplets
Are there data on the heat flux so that the heating can indeed be estimated?
Citation: https://doi.org/10.5194/amt-2023-206-CC1 -
CC2: 'Reply on CC1', Jean-Francois Doussin, 22 Mar 2024
Thank you very much for your interest to our paper and for letting us know.
Indeed our cloud chamber quick overview was more focused on static chambers rather than flow chambers for a better comparison with the CESAM facilty but we will pay attention to mention Petten facility in the final version.
Concerning light source and its UV/IR content : Indeed, it is not described in this paper as it has been largely described and commented in previous CESAM papers (including the original description by Wang et al, 2011). We may consider to add it as supplementary information in the final version if it is considered needed.
Again thank you for helping us to improve the paper
Citation: https://doi.org/10.5194/amt-2023-206-CC2 -
CC3: 'Reply on CC2', Harry ten Brink, 22 Mar 2024
I suggest to provide brief summary of the UV source plus a comment that it also emits heat radation (IR?) as now given as reason for a different nucleation regime later on
Citation: https://doi.org/10.5194/amt-2023-206-CC3
-
CC3: 'Reply on CC2', Harry ten Brink, 22 Mar 2024
-
CC2: 'Reply on CC1', Jean-Francois Doussin, 22 Mar 2024
-
RC1: 'Comment on amt-2023-206', Anonymous Referee #1, 27 Mar 2024
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2023-206/amt-2023-206-RC1-supplement.pdf
-
RC2: 'Comment on amt-2023-206', Anonymous Referee #3, 02 May 2024
Mandariya et al. present a protocol for generating quasi-adiabatic expansion clouds in the CESAM chamber under irradiated and non-irradiated conditions. Further, they present six experiments, three under irradiated and three under non-irradiated conditions. Overall, the manuscript fails to provide sufficient evidence for the influence of irradiation during cloud activation. The manuscript is not well written and needs major improvements in its grammar, sentence structure, and overall wording. I strongly recommend that the authors perform a full editorial review before re-submission. All in all, I cannot recommend publication of the manuscript in its current form in AMT.
Major comments
The authors perform a series of experiments using their newly designed protocol in order to identify the influence of UV-cis irradiation on cloud activation. However, experimental characteristics that the authors them self label to be important for cloud activation (RH, dew point T, dP, dT, initial number concentration), differ significantly between all experiments. The authors fail to provide sufficient evidence that the difference in cloud activation is caused by irradiation rather than the difference in these characteristics. A detailed uncertainty analysis on the influence of these different characteristics needs to be provided.The authors frequently point out that the chamber is affected by inhomogeneities (e.g., humidity, temperature) and turbulences. Due to the influence of these parameters on cloud activation, it is questionable if the CESAM chamber is an optimal choice for these experiments. A detailed characterization of these turbulences and inhomogeneities is required to identify their influence on cloud activation.
Specific comments
Line 42-44: Is there a more recent estimate on the re-evaporation of clouds? Do you have an estimate how often a CCN might be processed by multiple clouds?
Line 92: What does the abbreviation CESAM stand for?
Figure 3: Is this figure really necessary, considering that you provide similar figures later on?
Line 138: A background particle number concentration of 100 cm-3 is high. What impact do you expect this value has on cloud activation in CESAM?
Line 281-294: I recommend to first discuss the different experiments performed and than discuss a typical cloud run. Please provide a proper statement here on the intend of these experiments.
Line 306: Can you speculate on the reason behind this temperature increase? What influence has this on your conclusions?
Line 307-308: Why is this process not automated?
Table 1: What influence do you expect form the fundamentally different change in pressure for run IC-1, IC-2, and IC-3?
Line 354: You state that turbulent mixing and inhomogeneity affect the cloud evolution. Please provide an average mixing time of the chamber used.
Line 369-370: Can you comment on the impact of this assumption on your analysis?
Line 440-444: Again, please comment on the average chamber mixing time.
Line 493: Please provide the irradiation spectrum.Some technical corrections:
1st sentence: "an" is singular and refers to "clouds" plural. "droplets lifetime" should be "droplet lifetimes". "seeds particles" should be "seed particles".
Line 21: CCN is not defined
LIne 27: is "LC" supposed to be "IC"?
LIne 28: LWC is not defined
Line 30: "air/water partitioning of semi-volatile compounds, and it should be" the wording is awkward
Figure 1: In the text you mention that only one fan is used. In the figure, however, it looks as if there is a second fan slightly shaded. This is only shown if I open the pdf via a pdf-reader. If opened in the browser, it is not visible.
Figure 2: There are some artifacts in the figure. Like shadowed axis-labels etc. Again only visible when using a pdf-reader.Citation: https://doi.org/10.5194/amt-2023-206-RC2
Viewed
HTML | XML | Total | Supplement | BibTeX | EndNote | |
---|---|---|---|---|---|---|
384 | 87 | 43 | 514 | 48 | 26 | 21 |
- HTML: 384
- PDF: 87
- XML: 43
- Total: 514
- Supplement: 48
- BibTeX: 26
- EndNote: 21
Viewed (geographical distribution)
Country | # | Views | % |
---|
Total: | 0 |
HTML: | 0 |
PDF: | 0 |
XML: | 0 |
- 1