the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 21 Jun 2024
The Impact of Aerosol on Cloud Water: A Heuristic Perspective
Abstract. Aerosol-cloud interactions modulate the role of clouds in Earth's climate. We derive, evaluate, and apply a simple model to understand aerosol-mediated cloud water adjustments in stratocumulus based on only two prognostic equations for the integrated cloud water L and droplet number concentration N. The model is solved numerically and analytically, and agrees well with documented large-eddy simulation data and satellite retrievals. A tight relationship between adjustments at low and high N is found, revealing the influence of non-precipitation processes (primarily entrainment) on adjustments in precipitating clouds. Furthermore, it is shown that adjustments in non-precipitating clouds tend to be positively biased by external L or N perturbations, while adjustments in precipitating clouds are barely susceptible. By deliberately reducing the complexity of the underlying system, this study constitutes a way forward to facilitate process-level understanding of cloud water adjustments.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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Supplement
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(6438 KB) - Metadata XML
-
Supplement
(1653 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2024-1725', Anonymous Referee #1, 21 Aug 2024
- AC1: 'Reply on RC1', Fabian Hoffmann, 13 Sep 2024
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RC2: 'Comment on egusphere-2024-1725', Anonymous Referee #2, 25 Aug 2024
General comments:
This study heuristically devised a simple model describing the behavior of liquid water path (L) as a function of cloud droplet number concentration (N) with its parameters adjusted to previously performed LES simulations and perturbed to explore the system sensitivity. The simple model is also used to analyze how the system behaves depending on external forcing of L and N. As the main framework of this study, these analyses are performed in terms of the logarithmic sensitivity parameter of L with respect to N where the precipitation and thermodynamics controls are identified and linked with each other. This is a very interesting study that provides a useful process-level insight into the cloud water adjustment to aerosol perturbations. I only have some relatively minor comments (listed below) that mainly require further clarifications of some model setup. I would recommend the manuscript be published after these comments are appropriately addressed.
Specific points:
Line 27, Line 166: What is “inverted v”? I cannot find the description of “v”.
Line 166: Likewise above, what is “regular v”?
Line 65: Insert “Based on (2)” prior to “The thermodynamic carrying capacity is...”.
Line 90: “The source SN has been neglected for simplicity”: Does this mean that N is monotonically decreasing with time during the time integration according to (6)? If so, N should not reach the steady state. Please explain what happens with temporal evolution of N in this computational setup.
Line 106: “Without N dynamics”: Does this mean that only (3) is used without (6)? Please clarify.
Line 177: Would it be possible to write down the equation describing how the perturbation timescale (tprt) comes into the perturbation added (Δln(N)prt). It is unclear (at least for me) how the prescribed perturbation timescale is used in calculation of the perturbation.
Citation: https://doi.org/10.5194/egusphere-2024-1725-RC2 - AC2: 'Reply on RC2', Fabian Hoffmann, 13 Sep 2024
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2024-1725', Anonymous Referee #1, 21 Aug 2024
- AC1: 'Reply on RC1', Fabian Hoffmann, 13 Sep 2024
-
RC2: 'Comment on egusphere-2024-1725', Anonymous Referee #2, 25 Aug 2024
General comments:
This study heuristically devised a simple model describing the behavior of liquid water path (L) as a function of cloud droplet number concentration (N) with its parameters adjusted to previously performed LES simulations and perturbed to explore the system sensitivity. The simple model is also used to analyze how the system behaves depending on external forcing of L and N. As the main framework of this study, these analyses are performed in terms of the logarithmic sensitivity parameter of L with respect to N where the precipitation and thermodynamics controls are identified and linked with each other. This is a very interesting study that provides a useful process-level insight into the cloud water adjustment to aerosol perturbations. I only have some relatively minor comments (listed below) that mainly require further clarifications of some model setup. I would recommend the manuscript be published after these comments are appropriately addressed.
Specific points:
Line 27, Line 166: What is “inverted v”? I cannot find the description of “v”.
Line 166: Likewise above, what is “regular v”?
Line 65: Insert “Based on (2)” prior to “The thermodynamic carrying capacity is...”.
Line 90: “The source SN has been neglected for simplicity”: Does this mean that N is monotonically decreasing with time during the time integration according to (6)? If so, N should not reach the steady state. Please explain what happens with temporal evolution of N in this computational setup.
Line 106: “Without N dynamics”: Does this mean that only (3) is used without (6)? Please clarify.
Line 177: Would it be possible to write down the equation describing how the perturbation timescale (tprt) comes into the perturbation added (Δln(N)prt). It is unclear (at least for me) how the prescribed perturbation timescale is used in calculation of the perturbation.
Citation: https://doi.org/10.5194/egusphere-2024-1725-RC2 - AC2: 'Reply on RC2', Fabian Hoffmann, 13 Sep 2024
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Fabian Hoffmann
Franziska Glassmeier
Graham Feingold
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(6438 KB) - Metadata XML
-
Supplement
(1653 KB) - BibTeX
- EndNote
- Final revised paper