Dear Annett,

one Referee evaluated your revised manuscript. While it is acknowledged that you addressed most issues identified in the previous version and increased the scientific quality of your manuscript, the Referee is not fully convinced of your findings - particularly of your error estimation.
This second review pinpoints the remaining issues that should be addressed before your manuscript can be published in ACP. The most pressing issue seems to be the necessity to untangle (or at least thoroughly discuss) the different processes that might affect your results: diurnal changes in particle concentration and size as the result of boundary-layer processes, local emissions and photochemistry.

With best regards,
Matthias

Dear Anett,

It is my pleasure to accept you manuscript for publication in ACP.

Please consider the technical corrections below before uploading the final version of your manuscript.

With best regards,
Matthias


- line 175: Using f for relative humidity is rather uncommon and might lead to confusion with readers that are used to f being the enhancement factor.
- line 186: When you introduce Eq. (3), you should also introduce the meaning of \gamma
- lines 196, 197 and 204: please use same units as later in the manuscript (1/km)
- line 338: be?
- lines 351 - 353: Please elaborate or omit statement.
- lines 508 - 510: It is my understanding that you did not actually develop a parameterisation but rather determined factors that are used in an existing parameterisation. Please revise.
- line 645: Please provide Eq. (4) in simpler form. Also, I don't think that the factor 1/root(N) is appropriate if you simply apply error propagation. The number of used samples is already included in the error of the dry particle extinction coefficient. Please revise equation and error discussion accordingly.
- line 653: ambient instead of undisturbed?