Turbulent Energy Budget Analysis Based on Coherent Wind Lidar Observations

Xian, Jinhong; Qiu, Zongxu; Luo, Hongyan; Hu, Yuanyuan; Lin, Xiaoling; Lu, Chao; Yang, Yan; Yang, Honglong; Zhang, Ning

doi:https://doi.org/10.5194/egusphere-2024-2163

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https://doi.org/10.5194/egusphere-2024-2163

Preprints

18 Jul 2024

| 18 Jul 2024

Turbulent Energy Budget Analysis Based on Coherent Wind Lidar Observations

Jinhong Xian, Zongxu Qiu, Hongyan Luo, Yuanyuan Hu, Xiaoling Lin, Chao Lu, Yan Yang, Honglong Yang, and Ning Zhang

Abstract. The turbulent kinetic energy (TKE) budget term, as a key physical quantity for describing the generation and dissipation processes of turbulence, is crucial for revealing the essence and characteristics of turbulence. Due to limitations in current observational methods, the generation and dissipation mechanisms of atmospheric turbulent energy are mainly based on ground or tower-based observations, and studies on the budget terms of TKE of vertical structures are lacking. We propose a new method for detecting TKE budget terms based on coherent wind lidar, and compare it with data obtained with a three-dimensional ultrasonic anemometer. The results show that the lidar errors are relatively small, less than 0.0001 m²/s³, for at least 47 % of the data, which verifies the accuracy and reliability of our method. We explore the generation and dissipation mechanisms of turbulence under different weather conditions, and find that the buoyancy generation term plays a role in dissipating TKE under low cloud and light rain conditions. During the day, turbulent transport and the dissipation rate are the main dissipation terms, while buoyancy generation is the main dissipation term at night. The results show that the proposed method can accurately capture the vertical distribution of TKE, dissipation rate, shear generation, turbulent transport, and buoyancy generation terms in the boundary layer, and can comprehensively reflect the influence of each budget term on the vertical structure of turbulent energy. This research provides a new perspective and method for studies of atmospheric turbulence, which can be further applied to fine observations of the vertical structure and dynamics of turbulence.

Received: 12 Jul 2024 – Discussion started: 18 Jul 2024

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Jinhong Xian, Zongxu Qiu, Hongyan Luo, Yuanyuan Hu, Xiaoling Lin, Chao Lu, Yan Yang, Honglong Yang, and Ning Zhang

Status: closed

RC1:
'Comment on egusphere-2024-2163', Anonymous Referee #1, 28 Aug 2024
This manuscript presents a new method for obtaining turbulent kinetic energy (TKE) budget estimates from wind lidar measurements. The budget term estimates are compared to values based on ultrasonic anemometer data. The main benefit of the proposed new method is that it can provide values of the different terms of the TKE budget throughout the vertical column and not limited to point measurements such as from the ultrasonic anemometer. The manuscript is well written and easy to follow, with a clear structure and mostly clear figures.
My main concern with this manuscript is how the accuracy of the new lidar-based method compared to the established ultrasonic anemometer-based method is judged and communicated. In general, the basis on which the authors conclude that the method is accurate is somewhat vague and I would like to see more critical discussion of the results.
On multiple occasions (such as on lines 189, 219, and 234) it is stated that the lidar data is consistent with the ultrasonic anemometer data but this claim is vague; is it possible to quantify the agreement? And how do the authors view the discrepancies that do exist? For example, in Figure 5(a) there are multiple positive peaks in the momentum flux from the ultrasonic anemometer that the wind lidar does not capture, why is that? Please include some discussion of if there are any conditions under which this method may not be suitable to use (as well as some comment on possible deficiencies of the ultrasonic anemometer data, while that is a more established method it is not the "truth").
Furthermore, in the abstract and conclusions it is emphasized that the errors are “less than 0.0001 m2/s3, for at least 47% of the data”, which to me does not sound very convincing as it leaves the possibility that the remaining 53% of the data could have large errors. Figure 8 shows that this is not the case, but I recommend that the authors comment on this both in the abstract and in the main body of the text. In the abstract and conclusions it should be made clear that those numbers pertain to the buoyancy term as this is currently not mentioned.
Overall, I find this an interesting paper and the proposed method provides information that is useful for understanding the generation and dissipation of turbulence in different atmospheric conditions, and with the inclusion of a more rigorous discussion of the validity of the results as well as consideration of the specific comments below I find it suitable for publication.

Line by line comments:
Line 11: “The turbulent kinetic energy (TKE) budget term, as a key physical quantity […]” The subsequent sentences discuss budget terms in plural, should it be plural here as well? The use of the words “TKE budget term” is used at multiple occasions throughout the manuscript, please make it clear if you are referring to a specific term in the budget or the budget as a whole (for example on line 32).

Line 38: “(YSU, MYJ, MYNN2, ACM2, etc.)” These acronyms should be defined and ideally references for the schemes should be provided.

Line 107: What does “strong representativeness” mean? Please elaborate on what the data is representative of.

Line 134: When it says that “the wind speed measurements are checked every 30 min every day”, what is involved in the “checking”?

Line 143: Is “[29]” a literature reference? If so, please write it in the same format as the other references. If not, please explain what it means.

Figure 2: In this figure it is very difficult to judge the agreement between the blue and orange lines since they mostly overlap such that the orange line covers the blue one. Consider plotting the difference between the two lines (or some other measure of the difference) rather than the absolute values to facilitate comparison. To some extent this is true also for the other figures that compare two timeseries, but the problem is the biggest in Figure 2.

Line 174: θ_v usually denotes virtual potential temperature (so also in Stull, 1988 and Nilsson et al., 2016a which are referenced); it makes it easier for the reader if conventions for variable naming are kept.

Line 176: I believe it should be “tendency” rather than “tenacy”; also on Line 188 and in the caption to figure 3.

Line 185: The text says that Figure 3(a) shows data from the wind lidar obtained at both 150 and 160 m height but the figure seems to show only data from 150 m.

Figure 5: What is the value for delta z for the ultrasonic anemometer?

Line 266: Please provide a reference to the statement that the pressure transport tern is negligible in practical operations.

Line 276: “affect” should be “be affected by”, since B is derived as the residual and thus cannot affect the accuracy of the other terms.

Line 290: “gleamed” -> “gleaned”

Line 289-291: Please describe how the errors were calculated (what definition of the error is used).

Figure 8 caption: I find that this caption does not accurately describe the contents of this figure.

Paragraph starting with Line 311: The period after 12:00 is not mentioned in the text, please provide some comment on the interpretation of that part of the figure.

Figure 9: Since all the data is from the same day the date (2022/10/1) can be removed from the x-axis labels, this would make the hours on the axis easier to read (the same is true for figures 11 and 13).

Figure 9: Please emphasize somehow that the range of the color scales differs between the panels (and potentially change the color scales such that zero has the same color in all panels).

Line 331: “observed by (Nilsson et al., 2016a)” -> “observed by Nilsson et al. (2016a)”

Figure 10: A thin vertical indicating zero would be helpful for seeing if the terms are positive and negative.

Data availability statement: According to the ACP data policy, “The best way to provide access to data is by depositing them (as well as related metadata) in FAIR-aligned reliable public data repositories, assigning digital object identifiers, and properly citing data sets as individual contributions”. Providing the data in an easy to access format, in a public repository, is much preferable to providing it only upon request.
Citation: https://doi.org/10.5194/egusphere-2024-2163-RC1
- AC1: 'Reply on RC1', Jinhong Xian, 10 Oct 2024
  
  We would like to thank the reviewers and editor for their comments that have allowed us to further clarify some aspects of the manuscript in this revised version. Hereafter, we report reviewers' comments and our replies (in italics). For yours and reviewers’ convenience we have put the corresponding major changes introduced in red color in the revised version of the manuscript.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2163-AC1
RC2:
'Comment on egusphere-2024-2163', Anonymous Referee #2, 03 Oct 2024

A scientifically sound turbulent energy budget analysis is required for better understanding of the generation and dissipation processes of turbulence. However, current research on the generation and dissipation mechanisms of atmospheric turbulence energy is mainly based on ground or tower base observations, leading to unknown vertical TKE budget term. The authors propose a new method based on coherent wind lidar to detect TKE budget terms and compare them with data from a three-dimensional ultrasonic anemometer for verification. The results indicate that their proposed method can comprehensively reflect the impact of each budget term on the vertical structure of TKE, providing a new perspective and method for atmospheric turbulence research. The expression of this paper is clear, the argument is reasonable. It is suitable for publication. I think there are some small issues that can be improved, which is shown as follows:
Minor comments:
1． Lines 176 and 188 : “tenacy” should be “tendency”.
2． In section 3.7 Determination of the Buoyancy Generation Term: I suggest the authors elaborate on the sources of errors.
3． Figure 8 shows that at the height of 160 m, 48% of the results have an error of less than 0.0001 m2/s3; At the height of 320 m, 47% of the results have an error of less than 0.0001 m2/s3. The error statistical method is not rigorous enough and should be given as mean error or standard deviation.
4． The caption of Figure 8 does not effectively convey the meaning of this figure.
5． Lines 293 and 294 : How do you calculate the error? The calculation method for the error should be provided in the text.
6． Can this method proposed here be applicable in other circumstances? e.g., How about the implications for elucidating the turbulence-convection interaction, and convection initiation?
7. Lines 53-56: "...including changes in surface heat flux, atmospheric stability, and topography". More recent references are needed to support this statement. The authors can refer to https://doi.org/10.5194/acp-21-17079-2021.
8. Lines 58-59: Radar wind profiler can provide such high-resolution turbulence measurements (doi:10.1016/j.uclim.2022.101151), and can be mentioned here.

Citation: https://doi.org/10.5194/egusphere-2024-2163-RC2
- AC2: 'Reply on RC2', Jinhong Xian, 10 Oct 2024
  
  We would like to thank the reviewers and editor for their comments that have allowed us to further clarify some aspects of the manuscript in this revised version. Hereafter, we report reviewers' comments and our replies (in italics). For yours and reviewers’ convenience we have put the corresponding major changes introduced in red color in the revised version of the manuscript.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2163-AC2

Status: closed

RC1:
'Comment on egusphere-2024-2163', Anonymous Referee #1, 28 Aug 2024
This manuscript presents a new method for obtaining turbulent kinetic energy (TKE) budget estimates from wind lidar measurements. The budget term estimates are compared to values based on ultrasonic anemometer data. The main benefit of the proposed new method is that it can provide values of the different terms of the TKE budget throughout the vertical column and not limited to point measurements such as from the ultrasonic anemometer. The manuscript is well written and easy to follow, with a clear structure and mostly clear figures.
My main concern with this manuscript is how the accuracy of the new lidar-based method compared to the established ultrasonic anemometer-based method is judged and communicated. In general, the basis on which the authors conclude that the method is accurate is somewhat vague and I would like to see more critical discussion of the results.
On multiple occasions (such as on lines 189, 219, and 234) it is stated that the lidar data is consistent with the ultrasonic anemometer data but this claim is vague; is it possible to quantify the agreement? And how do the authors view the discrepancies that do exist? For example, in Figure 5(a) there are multiple positive peaks in the momentum flux from the ultrasonic anemometer that the wind lidar does not capture, why is that? Please include some discussion of if there are any conditions under which this method may not be suitable to use (as well as some comment on possible deficiencies of the ultrasonic anemometer data, while that is a more established method it is not the "truth").
Furthermore, in the abstract and conclusions it is emphasized that the errors are “less than 0.0001 m2/s3, for at least 47% of the data”, which to me does not sound very convincing as it leaves the possibility that the remaining 53% of the data could have large errors. Figure 8 shows that this is not the case, but I recommend that the authors comment on this both in the abstract and in the main body of the text. In the abstract and conclusions it should be made clear that those numbers pertain to the buoyancy term as this is currently not mentioned.
Overall, I find this an interesting paper and the proposed method provides information that is useful for understanding the generation and dissipation of turbulence in different atmospheric conditions, and with the inclusion of a more rigorous discussion of the validity of the results as well as consideration of the specific comments below I find it suitable for publication.

Line by line comments:
Line 11: “The turbulent kinetic energy (TKE) budget term, as a key physical quantity […]” The subsequent sentences discuss budget terms in plural, should it be plural here as well? The use of the words “TKE budget term” is used at multiple occasions throughout the manuscript, please make it clear if you are referring to a specific term in the budget or the budget as a whole (for example on line 32).

Line 38: “(YSU, MYJ, MYNN2, ACM2, etc.)” These acronyms should be defined and ideally references for the schemes should be provided.

Line 107: What does “strong representativeness” mean? Please elaborate on what the data is representative of.

Line 134: When it says that “the wind speed measurements are checked every 30 min every day”, what is involved in the “checking”?

Line 143: Is “[29]” a literature reference? If so, please write it in the same format as the other references. If not, please explain what it means.

Figure 2: In this figure it is very difficult to judge the agreement between the blue and orange lines since they mostly overlap such that the orange line covers the blue one. Consider plotting the difference between the two lines (or some other measure of the difference) rather than the absolute values to facilitate comparison. To some extent this is true also for the other figures that compare two timeseries, but the problem is the biggest in Figure 2.

Line 174: θ_v usually denotes virtual potential temperature (so also in Stull, 1988 and Nilsson et al., 2016a which are referenced); it makes it easier for the reader if conventions for variable naming are kept.

Line 176: I believe it should be “tendency” rather than “tenacy”; also on Line 188 and in the caption to figure 3.

Line 185: The text says that Figure 3(a) shows data from the wind lidar obtained at both 150 and 160 m height but the figure seems to show only data from 150 m.

Figure 5: What is the value for delta z for the ultrasonic anemometer?

Line 266: Please provide a reference to the statement that the pressure transport tern is negligible in practical operations.

Line 276: “affect” should be “be affected by”, since B is derived as the residual and thus cannot affect the accuracy of the other terms.

Line 290: “gleamed” -> “gleaned”

Line 289-291: Please describe how the errors were calculated (what definition of the error is used).

Figure 8 caption: I find that this caption does not accurately describe the contents of this figure.

Paragraph starting with Line 311: The period after 12:00 is not mentioned in the text, please provide some comment on the interpretation of that part of the figure.

Figure 9: Since all the data is from the same day the date (2022/10/1) can be removed from the x-axis labels, this would make the hours on the axis easier to read (the same is true for figures 11 and 13).

Figure 9: Please emphasize somehow that the range of the color scales differs between the panels (and potentially change the color scales such that zero has the same color in all panels).

Line 331: “observed by (Nilsson et al., 2016a)” -> “observed by Nilsson et al. (2016a)”

Figure 10: A thin vertical indicating zero would be helpful for seeing if the terms are positive and negative.

Data availability statement: According to the ACP data policy, “The best way to provide access to data is by depositing them (as well as related metadata) in FAIR-aligned reliable public data repositories, assigning digital object identifiers, and properly citing data sets as individual contributions”. Providing the data in an easy to access format, in a public repository, is much preferable to providing it only upon request.
Citation: https://doi.org/10.5194/egusphere-2024-2163-RC1
- AC1: 'Reply on RC1', Jinhong Xian, 10 Oct 2024
  
  We would like to thank the reviewers and editor for their comments that have allowed us to further clarify some aspects of the manuscript in this revised version. Hereafter, we report reviewers' comments and our replies (in italics). For yours and reviewers’ convenience we have put the corresponding major changes introduced in red color in the revised version of the manuscript.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2163-AC1
RC2:
'Comment on egusphere-2024-2163', Anonymous Referee #2, 03 Oct 2024

A scientifically sound turbulent energy budget analysis is required for better understanding of the generation and dissipation processes of turbulence. However, current research on the generation and dissipation mechanisms of atmospheric turbulence energy is mainly based on ground or tower base observations, leading to unknown vertical TKE budget term. The authors propose a new method based on coherent wind lidar to detect TKE budget terms and compare them with data from a three-dimensional ultrasonic anemometer for verification. The results indicate that their proposed method can comprehensively reflect the impact of each budget term on the vertical structure of TKE, providing a new perspective and method for atmospheric turbulence research. The expression of this paper is clear, the argument is reasonable. It is suitable for publication. I think there are some small issues that can be improved, which is shown as follows:
Minor comments:
1． Lines 176 and 188 : “tenacy” should be “tendency”.
2． In section 3.7 Determination of the Buoyancy Generation Term: I suggest the authors elaborate on the sources of errors.
3． Figure 8 shows that at the height of 160 m, 48% of the results have an error of less than 0.0001 m2/s3; At the height of 320 m, 47% of the results have an error of less than 0.0001 m2/s3. The error statistical method is not rigorous enough and should be given as mean error or standard deviation.
4． The caption of Figure 8 does not effectively convey the meaning of this figure.
5． Lines 293 and 294 : How do you calculate the error? The calculation method for the error should be provided in the text.
6． Can this method proposed here be applicable in other circumstances? e.g., How about the implications for elucidating the turbulence-convection interaction, and convection initiation?
7. Lines 53-56: "...including changes in surface heat flux, atmospheric stability, and topography". More recent references are needed to support this statement. The authors can refer to https://doi.org/10.5194/acp-21-17079-2021.
8. Lines 58-59: Radar wind profiler can provide such high-resolution turbulence measurements (doi:10.1016/j.uclim.2022.101151), and can be mentioned here.

Citation: https://doi.org/10.5194/egusphere-2024-2163-RC2
- AC2: 'Reply on RC2', Jinhong Xian, 10 Oct 2024
  
  We would like to thank the reviewers and editor for their comments that have allowed us to further clarify some aspects of the manuscript in this revised version. Hereafter, we report reviewers' comments and our replies (in italics). For yours and reviewers’ convenience we have put the corresponding major changes introduced in red color in the revised version of the manuscript.
  
  Citation: https://doi.org/10.5194/egusphere-2024-2163-AC2

Jinhong Xian, Zongxu Qiu, Hongyan Luo, Yuanyuan Hu, Xiaoling Lin, Chao Lu, Yan Yang, Honglong Yang, and Ning Zhang

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Short summary

The existing methods for observing turbulent kinetic energy budget term can only rely on ground-based tower. We have developed a new detection method that can directly observe and analyze the generation and dissipation mechanisms of turbulent energy at different heights in the vertical direction of the boundary layer. This research result will extend our study of turbulent kinetic energy budget terms from near ground to high altitude, providing a higher and more detailed perspective.


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