The role of ascent timescale for WCB moisture transport into the UTLS

Schwenk, Cornelis; Miltenberger, Annette

doi:https://doi.org/10.5194/egusphere-2024-2402

Preprints

https://doi.org/10.5194/egusphere-2024-2402

Preprints

23 Aug 2024

| 23 Aug 2024

The role of ascent timescale for WCB moisture transport into the UTLS

Cornelis Schwenk and Annette Miltenberger

Abstract. Warm conveyor belts (WCBs) are coherent ascending airstreams in extratropical cyclones. They are a major source of moisture for the extratropical upper troposphere and lower stratosphere (UTLS), where moisture acts as a potent greenhouse gas and WCB-associated cirrus contribute to cloud radiative forcing. However, the processes controlling WCB moisture transport and cloud properties are poorly characterised. Furthermore, recent studies have revealed (embedded) convection as a ubiquitous feature of WCBs, highlighting the importance of understanding their updraft and microphysical structure. We present a Lagrangian investigation of WCB moisture transport for a case from the WISE (Wave-driven ISentropic Exchange) campaign based on a convection-permitting simulation. Lagrangian non-dimensional metrics of the moisture budget suggest that the ascent timescale (τ₆₀₀) strongly controls the end-of-ascent total moisture content, which is largest for slowly ascending trajectories (τ₆₀₀ > 20 h, ~30 % of all WCB trajectories). This is due to relatively warm end-of-ascent temperatures and the strong temperature control on transported water vapor. Deviations from equilibrium water vapor – condensate partitioning are largest for slow trajectories due to faster glaciation and lower ice crystal numbers. A local moisture transport minimum at intermediate tau₆₀₀ results from a shift towards a riming dominated precipitation formation pathway and decreasing outflow temperatures with decreasing τ₆₀₀. The fastest trajectories (τ₆₀₀ < 5 h, ~5 % of all WCB trajectories) transport the largest condensate mass to the UTLS due to less efficient condensate loss, and produce the longest-lived outflow cirrus. Models that parameterise convection may under-represent these processes, potentially impacting weather forecasts and climate predictions.

Received: 30 Jul 2024 – Discussion started: 23 Aug 2024

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.

Download & links

Preprint (PDF, 30604 KB)

Supplement (94 KB)

Download & links

Cornelis Schwenk and Annette Miltenberger

Status: closed

RC1:
'Comment on egusphere-2024-2402', Anonymous Referee #1, 13 Sep 2024

General Comments
This manuscript describes a Lagrangian analysis of trajectories within a Warm Conveyor Belt (WCB) of a 2017 case using the ICON model with online trajectories. The authors perform a variety of calculations that elucidate the microphysical properties for trajectories and compare those from fast ascending parcels with those that rise more slowly. The findings indicate that convective trajectories start lower in the atmosphere, but rise higher and have higher precipitation efficiency due to increased riming. Furthermore, the convective trajectories have more small ice, which means cirrus clouds are present longer due to less sedimentation, which is likely to have a longer-term radiative impact. Overall, I thought the manuscript was very interesting and contained some novel results that seem to be consistent with other papers who used different methods. I don't have any major concerns with the paper other than it is very dense. There were many sections that I had to read multiple times to ensure that I was understanding the main points, thus it might be worthwhile to consider trimming back some of these calculations and results to the main points that you want the audience to take away (I was most interested by the results I listed above).
Specific Comments
Lines 182-189: The paper would benefit from a discussion of how the ascent time begins and ends. It appears this is when w=0, but that is not clear. If this is true, Is there any issue in looking for the time when w=0? It seems like the parcel could undergo very small vertical motion for a long time here. This seems to be supported by some calculations here. Should that impact the normalized time coordinate?
Lines 369-370: Is this result shown in a figure?
Lines 387-389: This statement is reasonable, but have the authors performed any calculations to confirm this hypothesis? It seems like you could compute a buoyant acceleration for the trajectory.
Lines 414-428: I am not sure that I follow this discussion about ice supersaturation and what is the takeaway points. Please revise.
Lines 470-472: This result would seem to suggest that the amount of turbulent mixing is a function of how long the parcel spends in the planetary boundary layer. One might expect a slower trajectory to spend more time there compared to a fast-ascending trajectory. Have you investigated this point?
Line 524: Is this due to the convective parcels being at a lower temperature? Is this worth noting here?
Lines 611-612: Provide a citation for this statement?
Lines 700-708: For me, these results were potentially less interesting than others. Perhaps remove this from the conclusions section?
This study is based on a single case study. How representative is this of WCBs as a whole? Is this case an example with similar amounts of convection to a typical WCB? I think it is worth commenting on how broadly these results might be applicable to other WCBs.
Technical Corrections
Line 260: Is Qmathrmtot a latex error? I am not sure what this is.
Line 363: "trajectoriesthat" needs a space.
Line 420: The extra (104.7%) seems like an error.
Line 604-605: There appear to be two Latex compiling errors here.
Figure A: I would reconsider the two colorbars in these panels. They make it difficult to see the geography underneath it.

Citation: https://doi.org/10.5194/egusphere-2024-2402-RC1
- AC2:
  'Reply on RC1', Cornelis Schwenk, 14 Oct 2024
  Response to RC1:
  Thank you for your thoughtful and positive feedback on our manuscript. We are pleased to hear that you found the analysis interesting and the results novel, especially in relation to convective trajectories and their microphysical properties. Below, we address your specific comments in detail
  There were many sections that I had to read multiple times to ensure that I was understanding the main points, thus it might be worthwhile to consider trimming back some of these calculations and results to the main points that you want the audience to take away
  
  Thank you for this valuable feedback. This is a point that both reviewers have made, therefore we have carefully reviewed the manuscript with a focus on improving readability and reducing redundancy. We have shortened sections 5.2, 5.3, 5.4 and 5.5 and restructured key points to enhance clarity. However, we have retained certain sections that may seem extensive, as they contain what we believe are essential findings necessary for a comprehensive understanding of this study. We hope these revisions strike a balance between conciseness and thoroughness.
  Lines 182-189: The paper would benefit from a discussion of how the ascent time begins and ends. It appears this is when w=0, but that is not clear. If this is true, Is there any issue in looking for the time when w=0? It seems like the parcel could undergo very small vertical motion for a long time here. This seems to be supported by some calculations here. Should that impact the normalized time coordinate?
  
  Thank you for your observation. We have clarified that t=0 specifically marks the beginning of the tau_WCB ascent (see line 187-188 in the revised manuscript), which, as defined earlier in the paper, is the period surrounding tau_600 during which the ascent velocity is at least 8 hPa/h . This criterion ensures that we capture the main ascent in a consistent fashion across parcels, but avoid parcels experiencing very small vertical motion over extended periods. We took great care in the data analysis to ensure that the selection of tau_WCB properly captures significant ascent, avoiding the inclusion of periods with minimal vertical movement.
  Lines 369-370: Is this result shown in a figure?
  
  Yes, this result is discussed in the preceding paragraphs, which reference Figures 4 and C1a .We believe this result is clearly presented in the figures, and that the current format provides sufficient readability and clarity.
  Lines 387-389: This statement is reasonable, but have the authors performed any calculations to confirm this hypothesis? It seems like you could compute a buoyant acceleration for the trajectory.
  
  Thank you for your suggestion. While we did not perform explicit calculations for buoyant acceleration, we proposed this explanation based on well-established physical principles. If the reviewer deems it necessary, we could calculate a 'potential buoyancy' for each trajectory, making reasonable assumptions about latent heat release and environmental conditions during ascent. However, we believe that this would add unnecessary complexity for a point that aligns with widely accepted understanding. We have however added a citation to a study that makes a similar finding: see line 391, (Schäfler and Harnisch, 2014) in the revised manuscript.
  Lines 414-428: I am not sure that I follow this discussion about ice supersaturation and what is the takeaway points. Please revise.
  
  Thank you for your feedback. We have revised the paragraph (now in lines 415-435) and have introduced sub-paragraphs to improve readability and clarify the key takeaway points. Specifically, we aim to highlight: i) that the thermodynamic conditions at the end of the ascent (temperature, pressure) are the primary factors determining vapor content, and ii) that RHi distributions differ between convective and slow trajectories, with higher RHi in slow trajectories likely due to differences in ice content at the end of the ascent. We hope these changes make the discussion more comprehensible and the main points clearer.
  Lines 470-472: This result would seem to suggest that the amount of turbulent mixing is a function of how long the parcel spends in the planetary boundary layer. One might expect a slower trajectory to spend more time there compared to a fast-ascending trajectory. Have you investigated this point?
  
  Thank you for the insightful comment. Indeed, the amount of moisture lost to turbulence increases with the time spent in the planetary boundary layer, which explains why slower trajectories lose more moisture to turbulent mixing than faster ones. However, the lines in question refer to a peculiar behavior we observed in the slowest trajectories, where moisture loss to turbulent mixing decreases again. To investigate this, we calculated the average wind shear experienced by trajectories in each ascent-time bin and found that the slowest ascending trajectories encounter less wind shear (Fig C5). This suggests that the slowest trajectories may be more embedded within the large-scale, coherent flow of the WCB, rather than being influenced by smaller-scale turbulence.
  We have made some minor amendments to the paragraph (now in lines 460-470) to provide additional clarification and hope that these revisions make this point more easily understandable.
  Line 524: Is this due to the convective parcels being at a lower temperature? Is this worth noting here?
  
  We believe the reviewer is asking whether the lower temperatures of convective parcels might explain why precipitation efficiency (PE) decreases with shorter ascent times. Our analysis found no significant correlation between PE and temperature. While lower temperatures mean that the parcel can hold less vapor, this does not necessarily imply that a higher fraction of hydrometeors formed during the ascent must precipitate by the end (which is what PE quantifies). This is therefore not worth mentioning here.
  Lines 611-612: Provide a citation for this statement?
  
  This was an oversight and we have added the relevant citation (line 598 of the revised manuscript)
  Lines 700-708: For me, these results were potentially less interesting than others. Perhaps remove this from the conclusions section?
  
  Thank you for your feedback. The lines in question present key findings of the paper which are of particular relevance for those with a primary interest in cloud microphysics. This might only appeal to a subset of readers, but is no less important. If the reviewer feels this distinction is not clear, we can add a clarification to highlight that this part is of specific interest to those focused on cloud microphysics.
  This study is based on a single case study. How representative is this of WCBs as a whole? Is this case an example with similar amounts of convection to a typical WCB? I think it is worth commenting on how broadly these results might be applicable to other WCBs.
  
  Thank you for raising this important point. In this paper, our focus was not specifically on identifying the most climatologically representative WCB, but rather on analyzing a typical, non-extreme WCB event to explore moisture transport and the differences between convective and non-convective trajectories. We intentionally selected an open-ocean WCB for this study, as the majority of WCBs ascend over the open ocean. While we believe our findings offer valuable insights into WCB dynamics, we acknowledge that further research is needed to determine how broadly these results apply to the wider WCB population and if the results found in this paper can be verified by measurements. We are currently addressing these points for future publications. We have added the following after line 726 in the revised manuscript:
  The results presented in this paper are strictly only valid for the analysed WCB case, which we have selected to represent a typical, non-extreme event of an open-ocean WCB. While we believe our findings provide valuable insights into WCB moisture transport and may be applicable to similar WCB cases, the extent to which they apply to the larger WCB population remains to be addressed in future studies. Furthermore, some of the findings summarised above may depend on the particular parameterisation set-up used in the analysed simulation, such as the specific microphysics scheme and the absence of a deep convection parameterisation. The influence of these model-specific factors on our key findings is currently being assessed through model sensitivity experiments and comparisons with observational data.
  Response to Technical Corrections
  
  Thank you for pointing out these small errors; we have corrected them. Regarding Figures A*: we have adjusted the color scheme and other parameters to improve visual accessibility while ensuring that the plots remain clear for color-deficient viewers.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2402-AC2
RC2:
'Comment on egusphere-2024-2402', Anonymous Referee #2, 04 Oct 2024
Review of “The role of ascent timescale for WCB moisture transport into UTLS”
Authors: Cornelis Schwenk and Annette Miltenberger
Recommendation: Minor revision
This work investigates the characteristics of WCB parcels that reached upper troposphere or lower stratosphere with a Lagrangian online trajectories. The authors considered only trajectories ascended more than 600 hPa. They categorized the trajectories into two types: one is the fast convection type which has the shorter ascent time scales of trajectories, the other is slowly ascending trajectories which has the longer time scale. They quantified that 80 to 90 % of the moisture is lost by precipitation formation, while about 20 % is by turbulent mixing. The fraction of supersaturated trajectories is larger in slow than in convective trajectories. Convective trajectories contain larger ice crystal number concentration. The topic find interesting and suitable for the publication of ACP after minor revisions.
Specific comments
I think this paper is a bit too long and feels redundant. By shortening the main text and organizing the key points, I believe it will become easier for readers to understand.

(7): There is no explanation for the terms of Chy and Ev.

Line 317: eastern -> western?

Line 363: A space is needed between “trajectories” and “that”.

Line 385: A space is needed between “g” and “gk^-1”.

Please unify the formatting. For example there are two types of format such as “g kg^-1” and “g/kg”.

Figure 6: Because it is hard to find aqua lines in the figure, I recommend change the color of those lines.

Line 533: decrease -> increase?

Line 603: What is “Fig. ??”?

Line 604: What is “Fig. SX”?

Line 624, 625: Please correct the font of “kg^-1^”
Citation: https://doi.org/10.5194/egusphere-2024-2402-RC2
- AC1: 'Reply on RC2', Cornelis Schwenk, 14 Oct 2024
  
  Response to RC2:
  Thank you for your positive feedback and for finding our work suitable for publication in ACP. We are glad that you found the investigation of WCB trajectories and their characteristics interesting. We also thank you for your helpful comments and for identifying the technical errors (points 3-6 and 8-11) which we have now corrected. Below we respond to your comments 1), 2) and 7).
  1) I think this paper is a bit too long and feels redundant. By shortening the main text and organizing the key points, I believe it will become easier for readers to understand.
  Thank you for this valuable feedback. This is a point that both reviewers have made, therefore we have carefully reviewed the manuscript with a focus on improving readability and reducing redundancy. We have shortened sections 5.2, 5.3, 5.4 and 5.5 and restructured key points to enhance clarity. However, we have retained certain sections that may seem extensive, as they contain what we believe are essential findings necessary for a comprehensive understanding of the study. We hope these revisions strike a balance between conciseness and thoroughness.
  2) There is no explanation for the terms of Chy and Ev.
  Thank you for pointing out the potential for confusion. We have added a brief explanation of these terms and adjusted the text to clarify that their precise definitions can be found in Appendix B4.
  7) Figure 6: Because it is hard to find aqua lines in the figure, I recommend change the color of those lines.
  We have replaced the aqua color with light-green to enhance the visibility of the vapor line while ensuring accessibility for color-deficient viewers.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2402-AC1

Status: closed

RC1:
'Comment on egusphere-2024-2402', Anonymous Referee #1, 13 Sep 2024

General Comments
This manuscript describes a Lagrangian analysis of trajectories within a Warm Conveyor Belt (WCB) of a 2017 case using the ICON model with online trajectories. The authors perform a variety of calculations that elucidate the microphysical properties for trajectories and compare those from fast ascending parcels with those that rise more slowly. The findings indicate that convective trajectories start lower in the atmosphere, but rise higher and have higher precipitation efficiency due to increased riming. Furthermore, the convective trajectories have more small ice, which means cirrus clouds are present longer due to less sedimentation, which is likely to have a longer-term radiative impact. Overall, I thought the manuscript was very interesting and contained some novel results that seem to be consistent with other papers who used different methods. I don't have any major concerns with the paper other than it is very dense. There were many sections that I had to read multiple times to ensure that I was understanding the main points, thus it might be worthwhile to consider trimming back some of these calculations and results to the main points that you want the audience to take away (I was most interested by the results I listed above).
Specific Comments
Lines 182-189: The paper would benefit from a discussion of how the ascent time begins and ends. It appears this is when w=0, but that is not clear. If this is true, Is there any issue in looking for the time when w=0? It seems like the parcel could undergo very small vertical motion for a long time here. This seems to be supported by some calculations here. Should that impact the normalized time coordinate?
Lines 369-370: Is this result shown in a figure?
Lines 387-389: This statement is reasonable, but have the authors performed any calculations to confirm this hypothesis? It seems like you could compute a buoyant acceleration for the trajectory.
Lines 414-428: I am not sure that I follow this discussion about ice supersaturation and what is the takeaway points. Please revise.
Lines 470-472: This result would seem to suggest that the amount of turbulent mixing is a function of how long the parcel spends in the planetary boundary layer. One might expect a slower trajectory to spend more time there compared to a fast-ascending trajectory. Have you investigated this point?
Line 524: Is this due to the convective parcels being at a lower temperature? Is this worth noting here?
Lines 611-612: Provide a citation for this statement?
Lines 700-708: For me, these results were potentially less interesting than others. Perhaps remove this from the conclusions section?
This study is based on a single case study. How representative is this of WCBs as a whole? Is this case an example with similar amounts of convection to a typical WCB? I think it is worth commenting on how broadly these results might be applicable to other WCBs.
Technical Corrections
Line 260: Is Qmathrmtot a latex error? I am not sure what this is.
Line 363: "trajectoriesthat" needs a space.
Line 420: The extra (104.7%) seems like an error.
Line 604-605: There appear to be two Latex compiling errors here.
Figure A: I would reconsider the two colorbars in these panels. They make it difficult to see the geography underneath it.

Citation: https://doi.org/10.5194/egusphere-2024-2402-RC1
- AC2:
  'Reply on RC1', Cornelis Schwenk, 14 Oct 2024
  Response to RC1:
  Thank you for your thoughtful and positive feedback on our manuscript. We are pleased to hear that you found the analysis interesting and the results novel, especially in relation to convective trajectories and their microphysical properties. Below, we address your specific comments in detail
  There were many sections that I had to read multiple times to ensure that I was understanding the main points, thus it might be worthwhile to consider trimming back some of these calculations and results to the main points that you want the audience to take away
  
  Thank you for this valuable feedback. This is a point that both reviewers have made, therefore we have carefully reviewed the manuscript with a focus on improving readability and reducing redundancy. We have shortened sections 5.2, 5.3, 5.4 and 5.5 and restructured key points to enhance clarity. However, we have retained certain sections that may seem extensive, as they contain what we believe are essential findings necessary for a comprehensive understanding of this study. We hope these revisions strike a balance between conciseness and thoroughness.
  Lines 182-189: The paper would benefit from a discussion of how the ascent time begins and ends. It appears this is when w=0, but that is not clear. If this is true, Is there any issue in looking for the time when w=0? It seems like the parcel could undergo very small vertical motion for a long time here. This seems to be supported by some calculations here. Should that impact the normalized time coordinate?
  
  Thank you for your observation. We have clarified that t=0 specifically marks the beginning of the tau_WCB ascent (see line 187-188 in the revised manuscript), which, as defined earlier in the paper, is the period surrounding tau_600 during which the ascent velocity is at least 8 hPa/h . This criterion ensures that we capture the main ascent in a consistent fashion across parcels, but avoid parcels experiencing very small vertical motion over extended periods. We took great care in the data analysis to ensure that the selection of tau_WCB properly captures significant ascent, avoiding the inclusion of periods with minimal vertical movement.
  Lines 369-370: Is this result shown in a figure?
  
  Yes, this result is discussed in the preceding paragraphs, which reference Figures 4 and C1a .We believe this result is clearly presented in the figures, and that the current format provides sufficient readability and clarity.
  Lines 387-389: This statement is reasonable, but have the authors performed any calculations to confirm this hypothesis? It seems like you could compute a buoyant acceleration for the trajectory.
  
  Thank you for your suggestion. While we did not perform explicit calculations for buoyant acceleration, we proposed this explanation based on well-established physical principles. If the reviewer deems it necessary, we could calculate a 'potential buoyancy' for each trajectory, making reasonable assumptions about latent heat release and environmental conditions during ascent. However, we believe that this would add unnecessary complexity for a point that aligns with widely accepted understanding. We have however added a citation to a study that makes a similar finding: see line 391, (Schäfler and Harnisch, 2014) in the revised manuscript.
  Lines 414-428: I am not sure that I follow this discussion about ice supersaturation and what is the takeaway points. Please revise.
  
  Thank you for your feedback. We have revised the paragraph (now in lines 415-435) and have introduced sub-paragraphs to improve readability and clarify the key takeaway points. Specifically, we aim to highlight: i) that the thermodynamic conditions at the end of the ascent (temperature, pressure) are the primary factors determining vapor content, and ii) that RHi distributions differ between convective and slow trajectories, with higher RHi in slow trajectories likely due to differences in ice content at the end of the ascent. We hope these changes make the discussion more comprehensible and the main points clearer.
  Lines 470-472: This result would seem to suggest that the amount of turbulent mixing is a function of how long the parcel spends in the planetary boundary layer. One might expect a slower trajectory to spend more time there compared to a fast-ascending trajectory. Have you investigated this point?
  
  Thank you for the insightful comment. Indeed, the amount of moisture lost to turbulence increases with the time spent in the planetary boundary layer, which explains why slower trajectories lose more moisture to turbulent mixing than faster ones. However, the lines in question refer to a peculiar behavior we observed in the slowest trajectories, where moisture loss to turbulent mixing decreases again. To investigate this, we calculated the average wind shear experienced by trajectories in each ascent-time bin and found that the slowest ascending trajectories encounter less wind shear (Fig C5). This suggests that the slowest trajectories may be more embedded within the large-scale, coherent flow of the WCB, rather than being influenced by smaller-scale turbulence.
  We have made some minor amendments to the paragraph (now in lines 460-470) to provide additional clarification and hope that these revisions make this point more easily understandable.
  Line 524: Is this due to the convective parcels being at a lower temperature? Is this worth noting here?
  
  We believe the reviewer is asking whether the lower temperatures of convective parcels might explain why precipitation efficiency (PE) decreases with shorter ascent times. Our analysis found no significant correlation between PE and temperature. While lower temperatures mean that the parcel can hold less vapor, this does not necessarily imply that a higher fraction of hydrometeors formed during the ascent must precipitate by the end (which is what PE quantifies). This is therefore not worth mentioning here.
  Lines 611-612: Provide a citation for this statement?
  
  This was an oversight and we have added the relevant citation (line 598 of the revised manuscript)
  Lines 700-708: For me, these results were potentially less interesting than others. Perhaps remove this from the conclusions section?
  
  Thank you for your feedback. The lines in question present key findings of the paper which are of particular relevance for those with a primary interest in cloud microphysics. This might only appeal to a subset of readers, but is no less important. If the reviewer feels this distinction is not clear, we can add a clarification to highlight that this part is of specific interest to those focused on cloud microphysics.
  This study is based on a single case study. How representative is this of WCBs as a whole? Is this case an example with similar amounts of convection to a typical WCB? I think it is worth commenting on how broadly these results might be applicable to other WCBs.
  
  Thank you for raising this important point. In this paper, our focus was not specifically on identifying the most climatologically representative WCB, but rather on analyzing a typical, non-extreme WCB event to explore moisture transport and the differences between convective and non-convective trajectories. We intentionally selected an open-ocean WCB for this study, as the majority of WCBs ascend over the open ocean. While we believe our findings offer valuable insights into WCB dynamics, we acknowledge that further research is needed to determine how broadly these results apply to the wider WCB population and if the results found in this paper can be verified by measurements. We are currently addressing these points for future publications. We have added the following after line 726 in the revised manuscript:
  The results presented in this paper are strictly only valid for the analysed WCB case, which we have selected to represent a typical, non-extreme event of an open-ocean WCB. While we believe our findings provide valuable insights into WCB moisture transport and may be applicable to similar WCB cases, the extent to which they apply to the larger WCB population remains to be addressed in future studies. Furthermore, some of the findings summarised above may depend on the particular parameterisation set-up used in the analysed simulation, such as the specific microphysics scheme and the absence of a deep convection parameterisation. The influence of these model-specific factors on our key findings is currently being assessed through model sensitivity experiments and comparisons with observational data.
  Response to Technical Corrections
  
  Thank you for pointing out these small errors; we have corrected them. Regarding Figures A*: we have adjusted the color scheme and other parameters to improve visual accessibility while ensuring that the plots remain clear for color-deficient viewers.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2402-AC2
RC2:
'Comment on egusphere-2024-2402', Anonymous Referee #2, 04 Oct 2024
Review of “The role of ascent timescale for WCB moisture transport into UTLS”
Authors: Cornelis Schwenk and Annette Miltenberger
Recommendation: Minor revision
This work investigates the characteristics of WCB parcels that reached upper troposphere or lower stratosphere with a Lagrangian online trajectories. The authors considered only trajectories ascended more than 600 hPa. They categorized the trajectories into two types: one is the fast convection type which has the shorter ascent time scales of trajectories, the other is slowly ascending trajectories which has the longer time scale. They quantified that 80 to 90 % of the moisture is lost by precipitation formation, while about 20 % is by turbulent mixing. The fraction of supersaturated trajectories is larger in slow than in convective trajectories. Convective trajectories contain larger ice crystal number concentration. The topic find interesting and suitable for the publication of ACP after minor revisions.
Specific comments
I think this paper is a bit too long and feels redundant. By shortening the main text and organizing the key points, I believe it will become easier for readers to understand.

(7): There is no explanation for the terms of Chy and Ev.

Line 317: eastern -> western?

Line 363: A space is needed between “trajectories” and “that”.

Line 385: A space is needed between “g” and “gk^-1”.

Please unify the formatting. For example there are two types of format such as “g kg^-1” and “g/kg”.

Figure 6: Because it is hard to find aqua lines in the figure, I recommend change the color of those lines.

Line 533: decrease -> increase?

Line 603: What is “Fig. ??”?

Line 604: What is “Fig. SX”?

Line 624, 625: Please correct the font of “kg^-1^”
Citation: https://doi.org/10.5194/egusphere-2024-2402-RC2
- AC1: 'Reply on RC2', Cornelis Schwenk, 14 Oct 2024
  
  Response to RC2:
  Thank you for your positive feedback and for finding our work suitable for publication in ACP. We are glad that you found the investigation of WCB trajectories and their characteristics interesting. We also thank you for your helpful comments and for identifying the technical errors (points 3-6 and 8-11) which we have now corrected. Below we respond to your comments 1), 2) and 7).
  1) I think this paper is a bit too long and feels redundant. By shortening the main text and organizing the key points, I believe it will become easier for readers to understand.
  Thank you for this valuable feedback. This is a point that both reviewers have made, therefore we have carefully reviewed the manuscript with a focus on improving readability and reducing redundancy. We have shortened sections 5.2, 5.3, 5.4 and 5.5 and restructured key points to enhance clarity. However, we have retained certain sections that may seem extensive, as they contain what we believe are essential findings necessary for a comprehensive understanding of the study. We hope these revisions strike a balance between conciseness and thoroughness.
  2) There is no explanation for the terms of Chy and Ev.
  Thank you for pointing out the potential for confusion. We have added a brief explanation of these terms and adjusted the text to clarify that their precise definitions can be found in Appendix B4.
  7) Figure 6: Because it is hard to find aqua lines in the figure, I recommend change the color of those lines.
  We have replaced the aqua color with light-green to enhance the visibility of the vapor line while ensuring accessibility for color-deficient viewers.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2402-AC1

Cornelis Schwenk and Annette Miltenberger

Supplement

https://doi.org/10.5194/egusphere-2024-2402-supplement

Cornelis Schwenk and Annette Miltenberger

Viewed

Total article views: 384 (including HTML, PDF, and XML)

HTML	PDF	XML	Total	Supplement	BibTeX	EndNote
226	103	55	384	23	7	7

HTML: 226
PDF: 103
XML: 55
Total: 384
Supplement: 23
BibTeX: 7
EndNote: 7

Views and downloads (calculated since 23 Aug 2024)

Month	HTML	PDF	XML	Total
Aug 2024	83	39	7	129
Sep 2024	55	15	8	78
Oct 2024	74	41	13	128
Nov 2024	14	8	27	49

Cumulative views and downloads (calculated since 23 Aug 2024)

Month	HTML	PDF	XML	Total
Aug 2024	83	39	7	129
Sep 2024	55	15	8	78
Oct 2024	74	41	13	128
Nov 2024	14	8	27	49

Viewed (geographical distribution)

Total article views: 401 (including HTML, PDF, and XML) Thereof 401 with geography defined and 0 with unknown origin.

Country	#	Views	%

Latest update: 20 Nov 2024

Short summary

Warm conveyor belts (WCBs) transport moisture into the upper atmosphere, where it acts as a greenhouse gas. This transport is not well understood, and the role of rapidly rising air is unclear. We simulate a WCB and look at fast and slow rising air to see how moisture is (differently) transported. We find that for fast ascending air more ice particles reach higher into the atmosphere, and that frozen cloud particles are removed differently than during slow ascent, which has more water vapour.


Total:	0
HTML:	0
PDF:	0
XML:	0