This paper uses the CFODD (Contoured Frequency by Optical Depth Diagrams) to evaluate the ERF_ACI (effective radiative forcing due to aerosol cloud interactions) in a modern climate model. 13 perturbed parameter experiments are performed to evaluate the model ERF_ACI using the emergent constraints paradigm. The paper is timely and appears to have some interesting results. However, at the moment, there is a fundamental methodological issue that I cannot understand and therefore I cannot provide a full review until the methodology is clarified. Specifically, note Figure 3. There is something basic that I’m missing. Why are the ERF_ACI_SW values so small? I would expect negative values near 1 Wm^-2. Also why does ERF_ACI_SW differ between figures 3, and S7. Some of the ERF_ACI_SW are even positive in S7! I would think that you have 13 experiments so you should have 13 fixed values of ERF_ACI_SW. It is almost like the total ERF_ACI has been decomposed into components in some way, however I can find no description of this in the text. Until the methodology is further explained I can not complete this review. In addition I have a few specific comments below.

Additional specific comments:

Abstract: Abstract should be less than 250 words according to the ACP guidelines: https://www.atmospheric-chemistry-and-physics.net/policies/guidelines_for_authors.html

The following paper is very similar in scope and methods and should be cited in the introduction: Takahashi, H., A. Bodas-Salcedo, and G. Stephens, 2021: Warm Cloud Evolution, Precipitation, and Their Weak Linkage in HadGEM3: New Process-Level Diagnostics Using A-Train Observations. J. Atmos. Sci., 78, 2075–2087, https://doi.org/10.1175/JAS-D-20-0321.1.

Line 125: is there a reference for RANSAC? I think this is a python package but will not be familiar to the average reader.

Line 221: MODIS provides 3 different effective radius values from the 1.6, 2.1, and 3.7 micron channels. 2.1 micron is the ‘standard’ product. Which one are you using?

Line 260 and Figure 1: Is a SLWC defined as a cloud with optical depth > 0.3 and radar reflectivity > -30 dBZ? If this is correct can you mention this in the text. In this case I would assume that the identification of detectable cloud is nearly entirely limited by the radar reflectivity threshold whereas the optical depth threshold probably was the dominant limiting factor in the earlier study.

Figure 3: You should include an uncertainty range around the linear fit as gray shading. You should quote that uncertainty in the text.

Line 350: This idea of adjusting the estimate of the ERF_ACI based on this linear fit seems bizarre to me. The CNTRL experiment already agrees with the observed CFODD slope almost exactly. So to me the story of this paper is that this version of the model agrees very well with this particular metric which suggests that the auto conversion process is been simulated with relatively good fidelity.

The paper discusses the use of satellite retrievals to evaluate warm rain processes and constrain the ERFaci in the Energy Exascale Earth System Model version 2 (E3SMv2). It applies an updated Contoured Frequency by Optical Depth Diagrams (CFODD) analysis, in both observations and simulations, to provide observational constraints for droplet collection efficiency. The autoconversion parameterization is modified in a series of sensitivity experiments to evaluate the simulated CFODD with respect to the observed one. This allows to estimate a more accurate simulated ERFaci that is driven by warm rain processes.

Main comments:

The manuscript provides an adequate description of the model and the satellite data that are used, including their limitations. I appreciate the authors' approach using CFODD to constrain the simulations, it is elegant and provide interesting results. Nevertheless, the CTRL simulation seems to agree well with the observations. This is a good result for the model and the control coefficients. Shouldn’t this be the main conclusion of the study? Is there a physical meaning for choosing other coefficients, in this model or others? it would be interesting for discussion.

The paper would benefit from improved organization and clearer, more concise writing. Specifically, Section 4 (with the note that there is no Section 5 between sections 4 and 6) is lengthy and could be subdivided into subsections. The latter part of Section 4 could potentially be formed into a subsection that addresses the limitations of the study. Additionally, the introduction section should concentrate on past studies and their relevance to the current research. Paragraphs that discuss the results and the methodology of the present study could be removed from the introduction. Furthermore, the abstract appears overly detailed. Consider revising to make it more concise while still providing essential information.

The manuscript frequently directs the reader to key figures in the supplement. It may be advantageous to consider incorporating some of these figures into the main manuscript to enhance accessibility.

Including a brief description of the CFODD method would be beneficial for readers who may be less familiar with such diagrams. This addition could provide clarity and context for those who may not have an in-depth understanding of the CFODD method.

One of the modifications to CFODD applied by the authors is reducing the cloud optical thickness (COT) to 0.3. As the authors mention, this adjustment has a substantial impact on cloud occurrence. It is worth considering whether this modification could also influence the slope of the CFODD by altering the weight of the bins with low COT (does the fitting account for data density?). Clarification is also needed on whether COT represents the in-cloud mean or the grid mean values. Specifying the resolution of the data is missing and it is unclear how products with different resolutions are combined.

Additional specific comments:

L266: There is a reference typo that needs correction.

L309: The statement about how optically thin layers can have high reflectivities near the cloud top is unclear. It would be helpful to clarify whether this refers to the small optical thickness of thin layers at the top of deeper clouds. The entire sentence needs clarification for better understanding.

L310: The term "strange features" needs clarification. Specify and elaborate on what exactly is being referred to.

L315: It would be beneficial to explicitly mention that you are describing Figure 2 in this section for better guidance to the reader.

L337: Clarify the meaning of "ERFaciSW strengthens." Provide a physical explanation, particularly in relation to its impact on cloud cover and albedo. This clarification will enhance the understanding of the reader.

L348: It is recommended to reword this sentence and provide a clear explanation that the observed slopes are utilized to constrain the simulated ERFaci. This sentence essentially describes the core of the study.

L350: Suggest marking -0.067 on the Figure for clarity and reference.

L351: Clarify the meaning of the total ERFaci of -1.5 in the context of the discussion. Mention again that it is the difference between the simulations (as stated in Line 249). Address why this value cannot be deduced directly from Figure 3.

L352: Specify whether "correcting" means changing the coefficients in the autoconversion parameterization.

L390: Why "however"? The linear relationship applies to both medium-large and small Re.

L460: Elaborate on the statement that "simulated reflectivity profiles near the cloud top are decoupled from the cloud below." Provide a more detailed explanation of what is meant by "decoupled." This is the only instance where "decoupled" is mentioned in the manuscript.