Articles | Volume 26, issue 11
https://doi.org/10.5194/acp-26-7917-2026
© Author(s) 2026. This work is distributed under the Creative Commons Attribution 4.0 License.
Exploring the processes of liquid water path sensitivity to aerosol-cloud interactions using output from a high-resolution large-eddy simulation
Download
- Final revised paper (published on 10 Jun 2026)
- Preprint (discussion started on 14 Nov 2025)
Interactive discussion
Status: closed
Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor
| : Report abuse
-
RC1: 'Comment on egusphere-2025-5064', Anonymous Referee #1, 19 Dec 2025
- AC1: 'Reply on RC1', Sudhakar Dipu, 21 Feb 2026
-
RC2: 'Comment on egusphere-2025-5064', Anonymous Referee #2, 06 Jan 2026
- AC2: 'Reply on RC2', Sudhakar Dipu, 21 Feb 2026
Peer review completion
AR – Author's response | RR – Referee report | ED – Editor decision | EF – Editorial file upload
AR by Sudhakar Dipu on behalf of the Authors (21 Feb 2026)
Author's response
Author's tracked changes
Manuscript
ED: Referee Nomination & Report Request started (03 Mar 2026) by Luisa Ickes
RR by Anonymous Referee #2 (13 Mar 2026)
RR by Anonymous Referee #1 (19 Mar 2026)
ED: Publish subject to technical corrections (08 Apr 2026) by Luisa Ickes
AR by Sudhakar Dipu on behalf of the Authors (16 Apr 2026)
Manuscript
In this paper, diagnostics from high-resolution Large-Eddy Simulations (LES) are presented and analyzed to investigate aerosol impacts on LWP sensitivity in a non-precipitating, single-layer liquid cloud regime. The analysis focuses on the non-linear relationship between cloud droplet number concentration and LWP under contrasting aerosol conditions, highlighting distinct regimes of positive and negative LWP sensitivity. The results demonstrate how aerosol loading modulates droplet activation, cloud-top entrainment, and associated thermodynamic responses, thereby shifting the transition between LWP sensitivity regimes. These processes are shown to be highly relevant for understanding aerosol–cloud interactions and for improving the representation of cloud microphysical–dynamical coupling in climate models.
The topic of the manuscript is highly relevant, and the analysis is based on a unique modeling data set. However, I cannot recommend the manuscript for acceptance in its current form, as several aspects of the analysis require clarification. In addition, numerous minor errors and inconsistencies are present throughout the manuscript. I therefore strongly recommend careful proofreading and thorough checking of equations, units, and figures. Some of these issues are outlined below, but the list is by no means exhaustive.
I found it highly interesting that the transition from positive to negative LWP sensitivity occurs at different droplet number concentrations under different aerosol loadings. How does this behavior align with the commonly assumed entrainment feedback? This question is particularly relevant given that the transition occurs at Nd ≈ 300 cm⁻³ in the high-aerosol scenario. At such high concentrations, the mean droplet size is far from having a sedimentation velocity that would be dynamically significant and system shouldn’t be sensitive to changes in Nd.
More detail on the modeling approach is needed to better understand how methodological choices may influence the analysis. Specifically, how is Nd diagnosed from CCN? Is saturation adjustment applied in the cloud microphysics scheme? How is Nd treated during mixing and entrainment processes? What is the vertical resolution near the cloud top? Do updraft velocities differ between the simulations as a result of aerosol perturbations?
Line 35–36: “The numerous small droplets also lead to droplet sedimentation.”
Isn’t the opposite expected, with smaller droplets having reduced sedimentation velocities?
Line 36: “Enhance radiative cooling at the cloud top.”
This statement could be more precise, as radiative cooling occurs within a relatively thin layer near the cloud top.
Line 37: “Further, the entrainment of warm, dry air into the cloud leads to evaporation of the smaller droplets, resulting in decreases in LWP or negative LWP adjustment.”
Entrainment leads to LWP reduction even if all droplets lose mass homogeneously, not only through preferential evaporation of smaller droplets.
Line 49: “The Nd–LWP relationship is non-linear, and the co-variability between LWP and Nd primarily drives it.” While this is true, is it the co-variability between aerosol and meteorological conditions that fundamentally drives both LWP and Nd?
Line 53: Please clarify that the modeling referred to here concerns global, low-resolution models.
Line 95: Could the averaging of data to a coarser grid resolution affect the results? The original LES output likely resolves cloud-scale structures, but aggregation to 1.2 km places the analysis in the “gray zone” for cloud dynamical processes. Was the analysis repeated over smaller spatial scales to confirm that averaging does not affect?
Line 99–100: Why is this criterion used instead of one based on liquid water content? Such a layer may have very low LWC and therefore may not represent the actual cloud top, but rather a layer above it.
Line 102–104: This assumption is unlikely to hold over a one-day simulation. However, I did not find an analysis in the paper that could be affected.
Equation (2): Is the last term correct, given that vertical pressure velocity is used?
Equation (3): This equation appears to describe the mean volume diameter. If so, the subsequent calculation of the cloud dilution factor does not seem to be meaningful. Also the units appear incorrect.
Line 122: “Binned with a bin size of 1000.”
I assume this refers to the number of bins rather than the bin width; please clarify.
Line 143: The results are qualitatively consistent but far from being quantitatively consistent.
Line 148: “Which sustained droplet activation.”
The term sustained does not seem appropriate in this context.
Line 164: “Initially, both simulations exhibit positive LWP sensitivity.”
What is the reason for this behavior? Is it related to assumptions about the initial conditions? Are the initial thermodynamic profiles identical, differing only in aerosol loading?
Line 175: How are the different critical values determined? Are they derived across different spatial domains or over different time intervals?
Line 188: Related to the earlier comment on the definition of cloud top, how representative is Nd at cloud top of Nd throughout the cloud volume?
Line 192: This statement holds only if saturation adjustment is not used and condensation is explicitly calculated.
Line 195 onward: The effects of radiative cooling and heating are not discussed, despite being speculated as key mechanisms driving the negative Nd–LWP relationship. Why are these processes not analyzed in more detail?
Line 198: When discussing high-resolution simulations and processes occurring at the cloud edge, is advection the appropriate term, or would mixing be more accurate? More generally, modeling and also the analysis details may significantly affect the results, as numerical diffusion is unavoidable when Lagrangian processes are simulated in Eulerian framework. This may influence the diagnosed apparent heating and moisture sink terms.
Figure 1: Mean values could be added to both panels.
Figure 2: “the 1985 simulation uses the pre-industrial (1985) CCN”. This is a new definition for pre-industrial era.
Figure 6: left axis is cut of from the figure
Figure 7: ylabel “aparent”
Figure A1: Check the units.