|The authors have improved the manuscript and clarified some unclear sections. However, not all of my comments have been addressed in the manuscript; in addition, some obscurities remain and new ones were introduced by new text. |
The language has been improved somewhat. As I expect that copyediting of the manuscript will take care of it, I only listed a few wording or grammar mistakes below.
Line numbers in my comments refer to the marked-up version of the revised manuscript, attached to the response to the reviews.
The authors do a better job now pointing out the caveats of the new method. However, one limitation is the restriction to S = 0.07% (or lower). However, some more discussion should be given considering the following:
- In my previous comments, I had pointed out that CCN counters are least accurate at low S. This uncertainty in measurements should be mentioned.
- In addition, the authors mention at the very end of the manuscript that the low S makes this method ‘more applicable for ambient measurements of clouds and fogs in the atmosphere’. Typical supersaturations in clouds range from < 0.1% (e.g. for stratus) to > 1% (for cumulus clouds). This should be mentioned and appropriate references added.
- What is the reasoning that you can assume internal mixing of the aerosol? (e.g. l. 264)
- N(CCN) is rarely measured at cloud height as surface measurements are much simpler. It always remains the question whether surface aerosol is actually connected to clouds above the measurement site. However, I do not believe that just the transport time of bringing aerosol aloft (can be as little as a few minutes) is a sufficient ageing time - as implied in l. 268 - to achieve internal mixing. Please support or reject this assumption by appropriate references.
The discussion of delta(kappa) is still poorly organized. I suggest starting with the calculated delta(kappa) and its sensitivity studies and then concluding that an assumption of 0.2 is sufficiently good. That way, Section 3 will be better organized and also the conclusions could be structured better.
l. 21 and later in the manuscript: I don’t understand why it is restricted to ‘single source regions’. All what matters is whether the aerosol is aged or fresh – whereas the latter could originate from multiple emission sources.
l. 30: ‘nuclei’ is plural; either ‘nuclei are… ‘ or ‘nucleus is…’
l. 49: Why not adding the equation of the Angstrom exponent here (and remove it later)?
l. 51 and 52: What does R^2 refer to? In order to make it easier to read, I suggest splitting this sentence into (at least) two. That way it would also become clear what’ has’ in l. 52 refers to.
l. 62: As mentioned in my previous comments, aerosol hygroscopicity is defined as the ability of a particle (or a material in general) to take up a certain amount of water at a given RH. It is NOT a function of aerosol size as the text here suggests.
l. 68 and l. 108: Define parameters only once. Here you use two different names for rRH
l. 71 and remainder of the manuscript: ‘Composition’ is often used wrongly. ‘Component’ is the right word.
l. 172: Do you really refer to Eq.-1 here?
l. 221: I still don’t understand this sentence: what are ‘particles’ as opposed to ‘existing particles’?
l. 253-255: How is ‘too large’ or ‘too small’ defined?
l. 315: This is a very strong statement. Is this true under all conditions?
l. 318 and l. 325: In my previous comments, I had pointed out that ‘on the one hand’ and ‘on the other hand’ are used to introduce two opposing statements. However, here they introduce pretty much the same thing, i.e. the variation of kappa(c) can be quite large vs the influence of kappa(c) cannot be ignored. This should be restructured.
l. 335: A ‘cloud chamber’ is not the same as a CCN counter. In the former, a cloud is formed and the supersaturation cannot be exactly predetermined and/or measured. In a CCN counter, particles are exposed to a preset supersaturation. I assume you mean the latter here.
Technical (language) mistakes
l. 19: involves --> includes
l. 21: suitable
l. 77: ‘0.6 R^2’ seems very colloquial. Better is ‘R^2 = 0.6’.
l. 77: leads
l. 78: ..study that applied…
l. 81: ‘accurate’ might be better to use than ‘effective’
l. 82: rRH is directly connected
l. 159: Reword ‘..is found can be used’
l. 167: Define Dc here.
l. 203-205: This sentence needs to be rewritten as it is confusing: How can NCCN range to 100 nm (it is in [cm-3]); what are the units of a ‘cumulative contribution’ if it ranges from 0.2 to 0.8?
l. 217, 218: particles