the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 15 May 2023
Statistical Analysis on the Estimations of Solid Hydrometeors Growth Zones and Their Weather Conditions Using Radar Spectrum Width
Abstract. This study analyzes the correlation between hydrometeor type and radar spectrum width (σv) according to wind speed that can occur the atmospheric disturbances such as turbulence and wind shear. The σv zones shown as peak values were identified only in stratiform precipitation and they are highly related to the hydrometeor growth zones. Statistical analysis was performed for eight precipitation cases under various conditions (precipitation type, season), focusing on the Dendrite Growth Zone (DGZ) and the Needle Growth Zone (NGZ), where Dendrite (DN) and Needle (NE) type snowflakes are dominant, respectively. They were determined by the Growth Zone Determination Algorithm (GZDA) that was proposed in this study.
The intensity of the σv depends on atmospheric conditions (i.e., wind speed) and season (i.e., temperature). The high σv and negative relationship with the differential radar reflectivity (ZDR) in the DGZ for all cases is consistent with the aerodynamic properties of DN. As the range of σv was larger than that of ZDR, it was confirmed that the dependence of σv according to atmospheric conditions is significant. Contrastingly, the NGZ had a low σv and weak σv-ZDR negative relationship with a narrow range of σv, which is consistent with the aerodynamic properties of NE. The lower cross-correlation coefficient (ρhv) in the DGZ than that in the NGZ implies that the irregularities (particle shape and aerodynamics features) of DN were more pronounced than those of NE.
Finally, as the altitudes of two growth zones were determined by temperature, the possibility of estimating sub-zero temperature by GZDA was confirmed.
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RC1: 'Comment on egusphere-2023-947', Anonymous Referee #1, 17 Jun 2023
The authors continue exploring their idea of identifying the ice growth areas in the clouds using Doppler spectrum width σv which was first described in their 2023 paper in Advances in Atmospheric Sciences. In the submitted manuscript, they added analysis of additional cases and investigated the relationship between σv and differential reflectivity ZDR and cross-correlation coefficient ρhv.
Doppler spectrum width was somewhat abandoned in weather radar studies of clouds and precipitation during the last two decades compared to emerging polarimetric variables demonstrating superb power for hydrometeor classification and quantification. Nevertheless, the spectrum width may provide some additional information about the microphysics of ice beyond its traditional use for quantifying turbulent eddy dissipation rate (EDR). It is quite possible that enhanced σv may signify the areas of supercooled water inside ice clouds because micro-updrafts associated with strong turbulence may produce sufficient super-saturation with respect to water. This is likely often the case in the dendritic growth zones (DGZ) where local buoyancy can be generated due to the strong release of latent heat caused by the rapid depositional growth of very anisotropic ice particles with large capacitance. The σv enhancement in DGZ is clearly visible in Fig. 5. However, the DGZ is much better recognized by the increase of ZDR and KDP as shown in the study by Griffin et al. (JAMC, 2018, p.31) which is not cited in the manuscript. According to Griffin et al., the value of ZDR in the DGZ is mainly determined by the height of the storm above DGZ. In the same Fig. 5, it is obvious that ZDR is maximal at the times of the lowest storm heights. Although the enhanced turbulence causes increase of σv and decrease of ZDR due to more random orientation of particles, this aerodynamic effect is not the primary one determining the magnitude of ZDR. The value of ZDR in the DGZ is primarily dependent on the relative contributions of the quasi-spherical ice generated above the DGZ and very anisotropic ice such as dendrites or hexagonal plates locally grown in the DGZ as explained in Griffin et al. (2018).
In addition to the regions of intense small-scale turbulence, σv can be high in areas of strong wind shear and the latter is the most common factor affecting σv in the cold-season stratiform clouds. There is no discussion on the connection of the vertical wind shear and σv in the manuscript.
I have too many concerns about this manuscript, some of which follow:
- The authors apparently experience big problems with English usage to the extent that it is very difficult to understand the meaning of many sentences due to awkward formulations. As an example, in lines 238 – 239 it is said that “The potential range of the GZs were defined by the average range of the GZs identified in this study”. What does it mean?
- One of the major conclusions of the article formulated in “Summary and Conclusions” is “…the variation range of ZDR in the DGZ was narrower than that of σv”. ZDR is measured in dB and σv – in m/s. This is a classical comparison of apples and oranges.
- The authors make a strong statement that high σv is an indication of growth zones (GZ) of ice. Has this been confirmed by in situ observations? What is meant by GZ? In line 312, they use the term “maturity of GZs”. How is this quantified?
- “Freezing level” means a particular altitude but the authors use this term for a deep layer with negative temperature.
- Lines 332 – 333: There is a completely weird statement: “Water vapor pressure depends on atmospheric pressure, meaning that the development of GZs can be determined by altitude”.
- Lines 340 -341. Another awkward and strange statement: “it suggests that radar-based sub-zero T estimation from GZDA might be possible”. What is this? The QVP methodology provides clear detection and delineation of the melting layer and GZDA has nothing to do with this.
- Temperature contours in Figs. 4 and 5 should be labeled.
- What is the reason for negative Zdr in Fig. 10? Calibration errors of Zdr?
- In Figs. 6 and 7, it would be better to use temperture instead of altitude at Y axis. Why not to label each panel in these plots as SW1, SW2, etc.?
The manuscript is extremely confusing and controversial, and I strongly oppose its publishing in its current form.
Citation: https://doi.org/10.5194/egusphere-2023-947-RC1 -
AC1: 'Reply on RC1', Sung-Ho Suh, 21 Sep 2023
Dear Referee Sir,
The authors would like to express our sincere gratitude for your consideration and effort to improve the quality of the paper.
The authors' responses to the referee's comments and the revised draft are submitted here so please find the attachments and notify me if you have any further comments.Sincerely yours,
Sung-Ho Suh
- AC3: 'Reply on AC1', Sung-Ho Suh, 22 Sep 2023
-
RC2: 'Comment on egusphere-2023-947', Andrew Heymsfield, 05 Sep 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-947/egusphere-2023-947-RC2-supplement.pdf
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AC2: 'Reply on RC2', Sung-Ho Suh, 21 Sep 2023
Dear Dr. Heymsfield,
It is a great honor to have our research reviewed by you so the authors would like to express our sincere gratitude for your consideration and effort to improve the quality of the paper.
The authors' responses to the referee's comments and the revised draft are submitted in here so please find the attachments and notify me if you have any further comments.Sincerely yours,
Sung-Ho Suh
-
AC2: 'Reply on RC2', Sung-Ho Suh, 21 Sep 2023
Status: closed
-
RC1: 'Comment on egusphere-2023-947', Anonymous Referee #1, 17 Jun 2023
The authors continue exploring their idea of identifying the ice growth areas in the clouds using Doppler spectrum width σv which was first described in their 2023 paper in Advances in Atmospheric Sciences. In the submitted manuscript, they added analysis of additional cases and investigated the relationship between σv and differential reflectivity ZDR and cross-correlation coefficient ρhv.
Doppler spectrum width was somewhat abandoned in weather radar studies of clouds and precipitation during the last two decades compared to emerging polarimetric variables demonstrating superb power for hydrometeor classification and quantification. Nevertheless, the spectrum width may provide some additional information about the microphysics of ice beyond its traditional use for quantifying turbulent eddy dissipation rate (EDR). It is quite possible that enhanced σv may signify the areas of supercooled water inside ice clouds because micro-updrafts associated with strong turbulence may produce sufficient super-saturation with respect to water. This is likely often the case in the dendritic growth zones (DGZ) where local buoyancy can be generated due to the strong release of latent heat caused by the rapid depositional growth of very anisotropic ice particles with large capacitance. The σv enhancement in DGZ is clearly visible in Fig. 5. However, the DGZ is much better recognized by the increase of ZDR and KDP as shown in the study by Griffin et al. (JAMC, 2018, p.31) which is not cited in the manuscript. According to Griffin et al., the value of ZDR in the DGZ is mainly determined by the height of the storm above DGZ. In the same Fig. 5, it is obvious that ZDR is maximal at the times of the lowest storm heights. Although the enhanced turbulence causes increase of σv and decrease of ZDR due to more random orientation of particles, this aerodynamic effect is not the primary one determining the magnitude of ZDR. The value of ZDR in the DGZ is primarily dependent on the relative contributions of the quasi-spherical ice generated above the DGZ and very anisotropic ice such as dendrites or hexagonal plates locally grown in the DGZ as explained in Griffin et al. (2018).
In addition to the regions of intense small-scale turbulence, σv can be high in areas of strong wind shear and the latter is the most common factor affecting σv in the cold-season stratiform clouds. There is no discussion on the connection of the vertical wind shear and σv in the manuscript.
I have too many concerns about this manuscript, some of which follow:
- The authors apparently experience big problems with English usage to the extent that it is very difficult to understand the meaning of many sentences due to awkward formulations. As an example, in lines 238 – 239 it is said that “The potential range of the GZs were defined by the average range of the GZs identified in this study”. What does it mean?
- One of the major conclusions of the article formulated in “Summary and Conclusions” is “…the variation range of ZDR in the DGZ was narrower than that of σv”. ZDR is measured in dB and σv – in m/s. This is a classical comparison of apples and oranges.
- The authors make a strong statement that high σv is an indication of growth zones (GZ) of ice. Has this been confirmed by in situ observations? What is meant by GZ? In line 312, they use the term “maturity of GZs”. How is this quantified?
- “Freezing level” means a particular altitude but the authors use this term for a deep layer with negative temperature.
- Lines 332 – 333: There is a completely weird statement: “Water vapor pressure depends on atmospheric pressure, meaning that the development of GZs can be determined by altitude”.
- Lines 340 -341. Another awkward and strange statement: “it suggests that radar-based sub-zero T estimation from GZDA might be possible”. What is this? The QVP methodology provides clear detection and delineation of the melting layer and GZDA has nothing to do with this.
- Temperature contours in Figs. 4 and 5 should be labeled.
- What is the reason for negative Zdr in Fig. 10? Calibration errors of Zdr?
- In Figs. 6 and 7, it would be better to use temperture instead of altitude at Y axis. Why not to label each panel in these plots as SW1, SW2, etc.?
The manuscript is extremely confusing and controversial, and I strongly oppose its publishing in its current form.
Citation: https://doi.org/10.5194/egusphere-2023-947-RC1 -
AC1: 'Reply on RC1', Sung-Ho Suh, 21 Sep 2023
Dear Referee Sir,
The authors would like to express our sincere gratitude for your consideration and effort to improve the quality of the paper.
The authors' responses to the referee's comments and the revised draft are submitted here so please find the attachments and notify me if you have any further comments.Sincerely yours,
Sung-Ho Suh
- AC3: 'Reply on AC1', Sung-Ho Suh, 22 Sep 2023
-
RC2: 'Comment on egusphere-2023-947', Andrew Heymsfield, 05 Sep 2023
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2023/egusphere-2023-947/egusphere-2023-947-RC2-supplement.pdf
-
AC2: 'Reply on RC2', Sung-Ho Suh, 21 Sep 2023
Dear Dr. Heymsfield,
It is a great honor to have our research reviewed by you so the authors would like to express our sincere gratitude for your consideration and effort to improve the quality of the paper.
The authors' responses to the referee's comments and the revised draft are submitted in here so please find the attachments and notify me if you have any further comments.Sincerely yours,
Sung-Ho Suh
-
AC2: 'Reply on RC2', Sung-Ho Suh, 21 Sep 2023
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