The methodology to retrieve cloud droplet number concentration from remote sensors, which is described in this study, is an important tool for the atmospheric sciences community  when studying the formation and evolution of cloud microphysical properties over extended lengths of time. Aircraft programs to measure these properties typically target a very limited subset of clouds. Complementing and adding to these in situ measurements with data from lidar and satellite is critical for improving our fundamental understanding of climate and weather.

As I do not feel qualified to give a detailed critique of the methodology itself, and the derivation that is done quite meticulously in this submission, the few comments, questions and suggestions that I have will not change any of the conclusions. I offer them mostly for clarification.

Line 76: "Nd (re) has uncertainties of 0.16(0.16) and 0.55 (0.18), respectively."  What are the units/dimensions of these uncertainties?  They can't be in units of cm-4 and they are too small to be percentages. Can you explain?

Line 211: "Observed thermodynamics". I am assuming that this refers to soundings that document the T/RH vertical profiles?  I return to this question further down when I ask for more information on how the uncertainty in this profile impacts the derived Nd.

Line 229: "For the prior estimate of Nd, we reason that coincident cloud condensation nuclei (CCN) measurements provide an upper limit on the droplet number in each situation.". This requires additional discussion because the CCN measurements are only relevant as an upper limit to Nd if the cloud base temperature and maximum updraft velocity is known, since the number of droplets activated depend on the CCN spectrum of concentration versus supersaturation (SS). Two sentence further a value of 0.2% was mentioned, but where did this number come from? Unless I overlooked it, no where in the article are vertical motions discussed. Yes, given the cloud base T/P you can estimate maximum LWC but not maximum % SS. Given the very nice correlation between the in situ measured Nds and those extracted from the remote sensors, maybe this is a moot point. Perhaps 0.2% is a good guess for the clouds studied on the Southern Ocean; regardless, a bit more discussion about the properties of the CCN in this region would be useful with regard to the conditions that activate them.

Figure 4 and line 316. "Ramp" is a term that I rarely see when aircraft measurements are conducted. I understand the intent but thin a single sentence that explain that a "ramp" is when the aircraft does a vertical profile through a cloud. What isn't clear is if these are multiple passes through a cloud at different altitudes or a constant climb or descent?

When looking at the uncertainty analysis, I was unable to tell if uncertainty in fad and the associated uncertainty in derived adiabatic liquid water is included. The adiabatic LWC is sensitive to the LCL, i.e. cloud base temperature and pressure. These can vary throughout the day and even from initial values derived from radiosondes. How does this uncertainty impact the subsequent uncertainty in Nd and re?

My last point is trivial but from my perspective as one who provides the community with instrumentation I would like the model and manufacturer listed along with the instrument discussed. The author explicitly mentions the Vaisala ceilometer but not the manufacturer or models of the micropulse lidar (MPL) and cloud droplet probe (CDP). I ask that these are added.

Please see the attached file.