|I would like to thank the authors for the different answers to the comments and the changes made in the article. The quality of the paper has increased and the results are now more robust and clear. Nevertheless, some of my comments have not been answered adequately or are not mentioned in the final article. I would like the authors to comment on few points I am referring to here. |
From the first general comment answer:
The uncertainty for Nd of 25 % is considered by the author, I find this value excessively low, especially when compared with Grovesnor et al. (2017) values: Their review ranges the uncertainty of Nd from 20 % to 75% from ground based radar measurements, please refer to Section 5 from their paper. The uncertainty of LWP leads to an uncertainty on Nd much greater than 25 % (especially for LWP in the range considered in the study). Also in Dong et al. (1997), they conclude to an uncertainty on Nd of 36 %. I would like to see a deeper analysis on the uncertainty of Nd for the different parameters. Also, I think the paragraph on the uncertainty from the answer should appear in the article and not only the last part about re.
Also, can you make explicit the formula you use to propagate the uncertainty of re on ACI? With a simple equation, I find an uncertainty on ACI between 0.01 and 0.01 for a change in re of 10% and Nccn of 0 % (optimistic), which is not negligible considering the value from figure 8-b and the conclusion in paragraph 3.3.6. I would like to see some clarifications here.
From the second general comment answer:
In the article (p. 17, l. 3 of the new document), the lack of vertical velocity measurements is mentioned. But, it can be retrieved from ECMWF (with LTS), it would not be directly at cloud base and will concern a large-scale value but did you look at this parameter? I would also be curious to see the effect of humidity on the results. Did you look at other meteorological parameters than LTS which can impact the ACI?
The stratus formation is enhanced by high LTS (Klein et al. 1993) and, therefore, more prone to high ACI, which is in line with the results presented. The results show that ACI is a function of LTS and a function of wabs. Moreover, from the Figures (a) and (b) from the answer of the second general comment, LTS and wabs seem correlated with each other. The effect of LTS on ACI does not seem negligible, maybe even larger than the effect of wabs on ACI. I think a discussion is needed about the conclusions of the article and the correlations from observation that are not necessarily causality, and that the observed effect can be inhibited or enhanced (Grysperdt, 2016). You mention it but I think it would help to see the ACI for the two regimes of wabs and constrained for two regimes of LTS to ensure that the results described by Figure 8 are not an artifact.
From specific comment:
I suggest to put the location SGP at the end of the second sentence: "… are selected over the Southern Great Plains region of the United States (SGP). The physicochemical…" Otherwise, the logic of the abstract is difficult to follow.
The answers of the following comment should appear in the text:
- the different resolution and uncertainty between KAZR and MMCR
- The comparison with aircraft measurements from Delle Monache et al. (2004) with a quantification of their results to asses the reliability of the measurements.
- The threshold you are using are from Dong et al. (2015), originally suggested by Jones et al. (2011)
- The uncertainty of ACI corresponds to the 95 % confidence interval.
Delle Monache, L., Perry, K. D., Cederwall, R. T., & Ogren, J. A. (2004). In situ aerosol profiles over the Southern Great Plains cloud and radiation test bed site: 2. Effects of mixing height on aerosol properties. Journal of Geophysical Research: Atmospheres, 109(D6), doi: 10.1029/2003JD004024.
Dong, X., Schwantes, A. C., Xi, B., & Wu, P. (2015). Investigation of the marine boundary layer cloud and CCN properties under coupled and decoupled conditions over the Azores. Journal of Geophysical Research: Atmospheres, 120(12), 6179-6191, doi: 10.1002/2014JD022939.
Dong, X., Ackerman, T. P., Clothiaux, E. E., Pilewskie, P., & Han, Y. (1997). Microphysical and radiative properties of boundary layer stratiform clouds deduced from ground‐based measurements. Journal of Geophysical Research: Atmospheres, 102(D20), 23829-23843, doi: 10.1029/97JD02119.
Grosvenor, D. P., Sourdeval, O., Zuidema, P., Ackerman, A., Alexandrov, M. D., Bennartz, R., ... & Deneke, H. (2018). Remote sensing of droplet number concentration in warm clouds: A review of the current state of knowledge and perspectives. Reviews of Geophysics, 56(2), 409-453, doi: 10.1029/2017RG000593.
Gryspeerdt, E., Quaas, J., & Bellouin, N. (2016). Constraining the aerosol influence on cloud fraction. Journal of Geophysical Research: Atmospheres, 121(7), 3566-3583, doi: 10.1002/2015JD023744.
Jones, C. R., Bretherton, C. S., & Leon, D. (2011). Coupled vs. decoupled boundary layers in VOCALS-REx. Atmospheric Chemistry and Physics, 11(14), 7143-7153, doi: 10.5194/acp-11-7143-2011.