the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 08 Jul 2024
Dynamical imprints on precipitation cluster statistics across a hierarchy of high-resolution simulations
Abstract. Tropical precipitation cluster area and intensity distributions follow power laws, but the physical processes responsible for this macroscopic behavior remain unknown.We analyze global simulations at ten-kilometer horizontal resolution that are configured to have drastically varying degrees of realism, ranging from global radiative-convective equilibrium to fully realistic atmospheric simulations, to investigate how dynamics influence precipitation statistics. We find the presence of stirring and large-scale vertical overturning, as associated with substantial planetary and synoptic-scale variability, to be key for having cluster statistics approach power laws. The presence of such large-scale dynamics is reflected in steep vertical velocity spectra. Large-scale rising and sinking modulate the column water vapor and temperature field, leading to a heterogeneous distribution of moist and dry patches and regions of strong mass flux, in which large precipitation clusters form. Our findings suggest that power laws in Earth’s precipitation cluster statistics stem from the robust power laws of atmospheric motions.
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RC1: 'Comment on egusphere-2024-2020', Anonymous Referee #1, 28 Sep 2024
This manuscript explores the connection between precipitation clusters and large-scale dynamics using a hierarchy of model configurations within ICON. The use of such a hierarchy is particularly unique and an important contribution to the field. The study finds that power laws of the precipitation cluster characteristics are strongly related to those that govern atmospheric motions. While this work represents an important advance in the field, I strongly feel that – as written – the manuscript glosses over a lot of the details and doesn’t describe the results presented in the figures sufficiently. I find that arguments that connect the precipitation clusters to atmospheric motion is weak and that more descriptive explanation is needed before it can be accepted for publication. Some additional minor comments are below:
L72-73: Is the time-averaged zonal-mean SST just for 1979? Or is it a climatology of a different time period?
L78-79: I think it is important to point to other studies in the paper that have used similar approaches, such as:
Shi and Bretherton (2014): https://doi.org/10.1002/2014MS000342
Reed and Chavas (2015): https://doi.org/10.1002/2015MS000519
Arnold and Randall (2015): https://doi.org/10.1002/2015MS000498
Chavas and Reed (2019): https://doi.org/10.1175/JAS-D-19-0001.1
L78-79: I feel that RCE_r should really be referred to as RCE_f since using constant Coriolis parameter mimics an f-plane.
L89: How do you know that 260 days is sufficient for the analysis presented?
L92: L87 above states that the data is output daily for the models, but here it is stated that hourly data is used for the observations. Is that right? How is this rectified?
L93: Why 30-min accumulations? If you are comparing to the model output, and the model output is instantaneous, should you try and match the length of the model timestep for the time scale?
L102: Should it say: “defined as at least a four-point connected”
L105: Since a cluster has a minimum of four connected pixels, you should use a different example than a single pixel here.
L141: Wording is confusing/incorrect here: “same modulo differences.”
Figure 4: T_b on y-axis is not defined.
L173-L179: Is there any connection between the scaling seen here and that typical for Kinetic Energy in the atmopshere? See Nastrom and Gage (1985): https://doi.org/10.1175/1520-0469(1985)042%3C0950:ACOAWS%3E2.0.CO;2 Also, note, there is some similarity between the slopes seen here and the -5/3 slope in Nastrom and Gage (1985) for mesoscale dynamics and turbulence.
Citation: https://doi.org/10.5194/egusphere-2024-2020-RC1 -
RC2: 'Comment on egusphere-2024-2020', Anonymous Referee #2, 02 Oct 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2020/egusphere-2024-2020-RC2-supplement.pdf
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AC1: 'Comment on egusphere-2024-2020', Claudia Stephan, 24 Nov 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2020/egusphere-2024-2020-AC1-supplement.pdf
Status: closed
-
RC1: 'Comment on egusphere-2024-2020', Anonymous Referee #1, 28 Sep 2024
This manuscript explores the connection between precipitation clusters and large-scale dynamics using a hierarchy of model configurations within ICON. The use of such a hierarchy is particularly unique and an important contribution to the field. The study finds that power laws of the precipitation cluster characteristics are strongly related to those that govern atmospheric motions. While this work represents an important advance in the field, I strongly feel that – as written – the manuscript glosses over a lot of the details and doesn’t describe the results presented in the figures sufficiently. I find that arguments that connect the precipitation clusters to atmospheric motion is weak and that more descriptive explanation is needed before it can be accepted for publication. Some additional minor comments are below:
L72-73: Is the time-averaged zonal-mean SST just for 1979? Or is it a climatology of a different time period?
L78-79: I think it is important to point to other studies in the paper that have used similar approaches, such as:
Shi and Bretherton (2014): https://doi.org/10.1002/2014MS000342
Reed and Chavas (2015): https://doi.org/10.1002/2015MS000519
Arnold and Randall (2015): https://doi.org/10.1002/2015MS000498
Chavas and Reed (2019): https://doi.org/10.1175/JAS-D-19-0001.1
L78-79: I feel that RCE_r should really be referred to as RCE_f since using constant Coriolis parameter mimics an f-plane.
L89: How do you know that 260 days is sufficient for the analysis presented?
L92: L87 above states that the data is output daily for the models, but here it is stated that hourly data is used for the observations. Is that right? How is this rectified?
L93: Why 30-min accumulations? If you are comparing to the model output, and the model output is instantaneous, should you try and match the length of the model timestep for the time scale?
L102: Should it say: “defined as at least a four-point connected”
L105: Since a cluster has a minimum of four connected pixels, you should use a different example than a single pixel here.
L141: Wording is confusing/incorrect here: “same modulo differences.”
Figure 4: T_b on y-axis is not defined.
L173-L179: Is there any connection between the scaling seen here and that typical for Kinetic Energy in the atmopshere? See Nastrom and Gage (1985): https://doi.org/10.1175/1520-0469(1985)042%3C0950:ACOAWS%3E2.0.CO;2 Also, note, there is some similarity between the slopes seen here and the -5/3 slope in Nastrom and Gage (1985) for mesoscale dynamics and turbulence.
Citation: https://doi.org/10.5194/egusphere-2024-2020-RC1 -
RC2: 'Comment on egusphere-2024-2020', Anonymous Referee #2, 02 Oct 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2020/egusphere-2024-2020-RC2-supplement.pdf
-
AC1: 'Comment on egusphere-2024-2020', Claudia Stephan, 24 Nov 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-2020/egusphere-2024-2020-AC1-supplement.pdf
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