the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
Determination of atmospheric column condensate using active and passive remote sensing technology
- 1School of Mechanical and Precision Instrument Engineering, Xi’an University of Technology, Xi’an 710048, China
- 2College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
- 1School of Mechanical and Precision Instrument Engineering, Xi’an University of Technology, Xi’an 710048, China
- 2College of Atmospheric Sciences, Lanzhou University, Lanzhou 730000, China
Abstract. To further exploit atmospheres cloud-water resources (CWR), it is necessary to correctly evaluate the amount of CWR in an area. CWR are hydrometeors that have not participated in precipitation formation at the surface and are suspended in the atmosphere to be exploited to maximize possible precipitation in the atmosphere (Zhou, Y., et al. (2020)). CWR includes three items: the existing hydrometeors at a time, the influx of atmospheric hydrometeors along the boundaries of the study area, and the mass of hydrometeors converted from water vapor through condensation or desublimation, defined as condensate. Condensate is the most important part of CWR. At present, there is a lack of effective observation methods for atmospheric column condensates, so the direct observation data of CWR are insufficient. The method for detecting atmospheric column condensate in the atmosphere is proposed and presented. The formation of condensate is closely related to atmospheric meteorological parameters (e.g., temperature and vertical airflow velocity). For stratiform clouds, the amount of atmospheric column condensate can be calculated by the saturated water vapor density and the ascending velocity at the cloud base and top. Active and passive remote sensing technology are applied to detect the mass of atmospheric column condensate. Combining millimetre-wave radar (MWR), lidar and microwave radiometers can well observe the vertical velocity and temperature at the cloud boundary. The detailed detection scheme and data calculation method are presented, and the presented method can realize the deduction of atmospheric column condensate. A case of cloud layer change before precipitation was monitored, and atmospheric column condensate was deduced and obtained. This is the first application, to our knowledge, to operate observations of atmospheric column condensates, which is significant for research on the hydrologic cycle and the assessment of cloud water resources.
Huige Di et al.
Status: closed
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RC1: 'Comment on amt-2021-397', Anonymous Referee #1, 10 Mar 2022
General Comments:
This study presents an observation method for detecting atmospheric column condensates by combining millimeter-wave radar (MWR), lidar and microwave radiometers. This work is interesting and meaningful. Especially, the authors stated that it is the first application to operate observations of atmospheric column condensates. However, there are some issues in this manuscript, as listed below, that need to be carefully considered. Moreover, the English should be improved substantially, especially for Abstract and Results and discussions. I think this manuscript can be considered for publication only if the author could adequately address the comments below.
Specific comments:
- Lines 16-18. The author specifically mentions stratiform clouds. Is their atmospheric columnar condensate calculated differently? Moreover, the atmospheric column condensate in stratiform clouds is calculated by the saturated water vapor density and vertical airflow velocity, but the saturated water vapor density is not mentioned in the later observed quantities in the abstract.
- The authors keep emphasizing that it is “atmospheric column condensate”, but the actual object of observation is cloud, so would it be more appropriate to change it to “cloud column condensate”?
- Figure 1. The authors should provide appropriate explanations for the schematic diagram. g., it is not clear whether the horizontal arrows of “Input or output airflow” represent total input or output, or just the horizontally oriented input or output.
- Lines 116-117. To my knowledge, the unit of saturated water vapor density is g/m3. Please check it.
- Lines 123-125. Please define Rv and give a reference to the equation’s source. Furthermore, e is the water vapor pressure, and its unit should be similar to hPa, not kg/m3. Please check it.
- Figure 2. Pcong means the net flux from t1 to t2, so the label “Columnar condensation water” in the figure seems inappropriate.
- Lines 182-183. Does the overline mean sum or average? What’s more, the formula is valid on the assumption that the detection errors of S and V do not vary with time and are independent of each other. This should be declared in advance.
- Figure 6. It seems difficult for the reader to understand in detail how the vertical velocity is obtained from the schematic. Additional instructions need to be provided.
- Lines 255-260. Reflections from raindrops can interfere with the signal, so how much uncertainty is there in wind speed measurements in rainy conditions?
- Lines 287-289. A result picture of the cloud phase state should be shown.
- Lines 295-297. The results of the microwave radiometer should be displayed and validated in Sect. 6. Moreover, how was the final temperature determined in figure 10? Is it a combination of rotational Raman lidar and microwave radiometer measurements?
- Figure 12. The y-axis label “Condensation water” seems inappropriate, since it is the water vapor flux. And why are there only positive flux values in the figure?
- Lines 326-329. (1) The authors say that “the condensate in the period from 21:00 to 23:00 was integrated” and that “rainfall at 06:00 a.m.”, but what about the water vapor input and output from 23:00 to 6:00. It should be clarified. (2) According to the description, the total amount of the maximum possible condensate counted in this manuscript was 88.2 g (2.94 mm). The atmospheric column condensate can be obtained by integrating the instantaneous water vapor flux. It is worth noting that the unit of instantaneous water vapor flux is g/m2/s, and its unit after integration with respect to time (s) should be g/m2. This indicates in a physical sense how many grams of water vapor is transmitted per square meter (input or output). So I don’t understand how the authors got the results in g or even mm.
Minor comments:
- Line 36 and Line 65. The abbreviations need to be defined in the abstract and then again at the first instance in the rest of the text.
- Line 78. The right side seems to be GMh. This is not accurate.
- Line 162. The abbreviation RH is not needed because it is not used later. The same situation in photomultiplier tubes (PMTs), pure rotational Raman (PRR) and so on.
- Line 252. The Wair needs to be defined at the first appearance.
- Lines 269-270. The caption should be improved.
- Line 277. The name should not be all caps, also in Line 304.
- Figure 10. In the title of the picture, “… cloud topon …” should be “… cloud top on …”. And drawing a 0-value line in the picture can better help the reader capture the information.
-
AC1: 'Reply on RC1', Yun Yuan, 18 Mar 2022
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2021-397/amt-2021-397-AC1-supplement.pdf
-
RC2: 'Comment on amt-2021-397', Anonymous Referee #2, 17 Mar 2022
This paper demonstrates a very interesting combined observation of atmospheric column condensate by using lidar, microwave radiometer, and millimeter-wave radar. The case study presented in this work opens up the feasibility for future research on the hydrologic cycle and the assessment of cloud water resources. The paper can be published after addressing following issues:
- Since the abbreviations for microwave radiometer and millimeter-wave radar are similar, I would suggest use their full names in the whole manuscript. I was often confused about which technique MWR is referred to.
- Figure 2, maybe the coherent Doppler lidar should be removed from this figure, as it is not utilized in the present work.
- (13), I am not sure whether the number “237.3” is correct or mistyped.
- Figure 8, maybe it is worth to add the cloud top in figure 8(a), particularly the part utilized in the evaluation.
- Figure 9, it is better to add the information about the measurement technique for the temperatures at the cloud base or top in figure legends. On the other hand, what about the temperature at the cloud base measured by the microwave radiometer? Could that be used for the evaluation?
- What about the measurement uncertainty of the vertical wind velocity, which seems to play a significant role on the final flux?
- In this work, the author utilizes the saturated water vapor density for the evaluation. Could it be feasible to utilize the humidity measured by e.g., DIAL for the evaluation, which may improve the accuracy? A brief discussion about the feasibility could be valuable.
-
AC2: 'Reply on RC2', Yun Yuan, 18 Mar 2022
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2021-397/amt-2021-397-AC2-supplement.pdf
Status: closed
-
RC1: 'Comment on amt-2021-397', Anonymous Referee #1, 10 Mar 2022
General Comments:
This study presents an observation method for detecting atmospheric column condensates by combining millimeter-wave radar (MWR), lidar and microwave radiometers. This work is interesting and meaningful. Especially, the authors stated that it is the first application to operate observations of atmospheric column condensates. However, there are some issues in this manuscript, as listed below, that need to be carefully considered. Moreover, the English should be improved substantially, especially for Abstract and Results and discussions. I think this manuscript can be considered for publication only if the author could adequately address the comments below.
Specific comments:
- Lines 16-18. The author specifically mentions stratiform clouds. Is their atmospheric columnar condensate calculated differently? Moreover, the atmospheric column condensate in stratiform clouds is calculated by the saturated water vapor density and vertical airflow velocity, but the saturated water vapor density is not mentioned in the later observed quantities in the abstract.
- The authors keep emphasizing that it is “atmospheric column condensate”, but the actual object of observation is cloud, so would it be more appropriate to change it to “cloud column condensate”?
- Figure 1. The authors should provide appropriate explanations for the schematic diagram. g., it is not clear whether the horizontal arrows of “Input or output airflow” represent total input or output, or just the horizontally oriented input or output.
- Lines 116-117. To my knowledge, the unit of saturated water vapor density is g/m3. Please check it.
- Lines 123-125. Please define Rv and give a reference to the equation’s source. Furthermore, e is the water vapor pressure, and its unit should be similar to hPa, not kg/m3. Please check it.
- Figure 2. Pcong means the net flux from t1 to t2, so the label “Columnar condensation water” in the figure seems inappropriate.
- Lines 182-183. Does the overline mean sum or average? What’s more, the formula is valid on the assumption that the detection errors of S and V do not vary with time and are independent of each other. This should be declared in advance.
- Figure 6. It seems difficult for the reader to understand in detail how the vertical velocity is obtained from the schematic. Additional instructions need to be provided.
- Lines 255-260. Reflections from raindrops can interfere with the signal, so how much uncertainty is there in wind speed measurements in rainy conditions?
- Lines 287-289. A result picture of the cloud phase state should be shown.
- Lines 295-297. The results of the microwave radiometer should be displayed and validated in Sect. 6. Moreover, how was the final temperature determined in figure 10? Is it a combination of rotational Raman lidar and microwave radiometer measurements?
- Figure 12. The y-axis label “Condensation water” seems inappropriate, since it is the water vapor flux. And why are there only positive flux values in the figure?
- Lines 326-329. (1) The authors say that “the condensate in the period from 21:00 to 23:00 was integrated” and that “rainfall at 06:00 a.m.”, but what about the water vapor input and output from 23:00 to 6:00. It should be clarified. (2) According to the description, the total amount of the maximum possible condensate counted in this manuscript was 88.2 g (2.94 mm). The atmospheric column condensate can be obtained by integrating the instantaneous water vapor flux. It is worth noting that the unit of instantaneous water vapor flux is g/m2/s, and its unit after integration with respect to time (s) should be g/m2. This indicates in a physical sense how many grams of water vapor is transmitted per square meter (input or output). So I don’t understand how the authors got the results in g or even mm.
Minor comments:
- Line 36 and Line 65. The abbreviations need to be defined in the abstract and then again at the first instance in the rest of the text.
- Line 78. The right side seems to be GMh. This is not accurate.
- Line 162. The abbreviation RH is not needed because it is not used later. The same situation in photomultiplier tubes (PMTs), pure rotational Raman (PRR) and so on.
- Line 252. The Wair needs to be defined at the first appearance.
- Lines 269-270. The caption should be improved.
- Line 277. The name should not be all caps, also in Line 304.
- Figure 10. In the title of the picture, “… cloud topon …” should be “… cloud top on …”. And drawing a 0-value line in the picture can better help the reader capture the information.
-
AC1: 'Reply on RC1', Yun Yuan, 18 Mar 2022
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2021-397/amt-2021-397-AC1-supplement.pdf
-
RC2: 'Comment on amt-2021-397', Anonymous Referee #2, 17 Mar 2022
This paper demonstrates a very interesting combined observation of atmospheric column condensate by using lidar, microwave radiometer, and millimeter-wave radar. The case study presented in this work opens up the feasibility for future research on the hydrologic cycle and the assessment of cloud water resources. The paper can be published after addressing following issues:
- Since the abbreviations for microwave radiometer and millimeter-wave radar are similar, I would suggest use their full names in the whole manuscript. I was often confused about which technique MWR is referred to.
- Figure 2, maybe the coherent Doppler lidar should be removed from this figure, as it is not utilized in the present work.
- (13), I am not sure whether the number “237.3” is correct or mistyped.
- Figure 8, maybe it is worth to add the cloud top in figure 8(a), particularly the part utilized in the evaluation.
- Figure 9, it is better to add the information about the measurement technique for the temperatures at the cloud base or top in figure legends. On the other hand, what about the temperature at the cloud base measured by the microwave radiometer? Could that be used for the evaluation?
- What about the measurement uncertainty of the vertical wind velocity, which seems to play a significant role on the final flux?
- In this work, the author utilizes the saturated water vapor density for the evaluation. Could it be feasible to utilize the humidity measured by e.g., DIAL for the evaluation, which may improve the accuracy? A brief discussion about the feasibility could be valuable.
-
AC2: 'Reply on RC2', Yun Yuan, 18 Mar 2022
The comment was uploaded in the form of a supplement: https://amt.copernicus.org/preprints/amt-2021-397/amt-2021-397-AC2-supplement.pdf
Huige Di et al.
Huige Di et al.
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