Dear authors,

thanks for revising the manuscript.

The main concern of the referees is the large lowest detectable size of 16.6 nm of the SMPS system. The referees are right that it is difficult to assess the aerosol formation with the measurements starting with such a large size. As a result, you have modified the manuscript and softened some of the conclusions.

I still recommend to add a note about the measurement size also to the abstract and the conclusions.

I have few additional comments that require some work.

line 51: Clarify what do you mean by urban pollution.
line 125: What do you mean that particle formation was found to take place on event and non-event days.
line 183: Confidence level typically implies statistical methods. Please modify the sentence.
line 188: how frequent were the bursts detected with the CPC?
line 223: What would the result be, if you would follow the mode through the night? Was growth typically persistent through the night? Setting a deadline for the midnight is rather arbitrary.

line 237: NSF was proposed by who? Please add a reference.

line 280: From where was ammonia data available from? Please add a short section on ancillary data to the methods section.

line 299: From where did you get the organic compounds? VOC data it seems, but this is not described. Please describe in the methods section.

line 315: Cluster 3 and following discussion is difficult to follow, but it clear after reading the section 3.3. Please summarise the trajectory analysis results here or consider structural changes.

line 320: again organic carbon concentration. From where?

line 323: low growth rate and consequently low survivability

line 329: How did you determine particulate organic carbon concentration?

line 341: With the instrument that detects > 16.6. nm size distribution, one cannot assess the initial states of newly formed particles.
line 358: Ethane, from where is the data from?

Table 1: A fraction of NPF days to all days would help to address the frequency at different locations.
Table 2: What is the variability of these numbers?

Figure 3: What is the variability of GR?

Figure 4: Mean or median? If the latter, quartile range would help to address the variability.

Figure 6: Same comment as Figure 3.

Figure 7: same as above.

yours,
-tuukka

Dear Authors,

thanks for a quick and very good revision of the manuscript.

Only few technical issues remain, which I trust that you will correct accordingly.

Please spell out the acronyms VOC and OC in the data sources as they appear there for the first time. Furthermore, spell out DEFRA to make it clear for the reader that it connects to UK Air, Department of Environment, Food and Rural Affairs.

Please check, if you need to add a text in the acknowledgement section.


-tuukka