The manuscript by Yttri et al. presents four years of observations of carbonaceous aerosols at an arctic site. The sources are investigated through measurements of specific organic source tracers combined with source apportionment and compared with dispersion modeling (FLEXPART). 

Overall the study is interesting and important, and my comments are generally to the presentation of the study. 

A very large number of abbreviations are used in the manuscript of which many are introduced already in the introduction. I suggest to reduce the number of abbreviations as it makes the manuscript difficult to read. Please also check that:

1.    all abbreviations are only introduced once (e.g. LRT is explained twice in the abstract).

2.    all abbreviations are actually used later in the text. If not, they are not necessary and just add to difficulty of reading the manuscript.

Line 116-152: These paragraphs argue about the importance of the present work, but the authors have chosen a somewhat critical tone towards previous studies to highlight the importance of the present work. The readers will appreciate this work without the negative tone towards previous studies. I suggest to revise accordingly. 

I suggest to add more information to introduce the source specific tracers in the introduction. This will be helpful for the readers to understand the results and discussion about e.g. ratios of levoglucosan and mannosan.

L440-449: Can local influence be completely excluded, in particular for RWC?

In general, it is useful to include standard deviations with average concentrations and contributions e.g. line 568-569.

Minor comments

Line 43-45: This introduction is confusing – “lack of long-term observations for many components such as OA” but then it is stated that the exception is eBC and MSA. I suggest to change “many” to “important” or similar. 

L57-58 “compared to 2017 to 2018, in 2019 and 2020” – please clarify.

L73-74 more important source to eBC?

L86: Please add references to all statements.

L95-96: It is not clear to me how the Ng and McFiggans papers support this statement. Please clarify in your response.

L96: These changes may? Otherwise a reference is needed.

L148: tricarboxylic acid (please add a space before acid)

L149: Hansen et al. ACP 2014 (already a reference) reported monoterpene oxidation products in aerosols collected at two Arctic sites during a full year. 

L224: Please add information about where standards were obtained.

L355-358: Please include the numbers here to make the comparison more clear. Were the Antarctica measurements part of the present study?

L363: Time series of EC, OC and sulfate?

L377: more efficient transport of polluted air masses?

L393: greatly. I suggest to change to considerably or significantly

L415-427: Please also explain the significance of the levoglucosan to mannosan ratio.

L439-440: Of EC?

L522: isoprene is the BVOC emitted in highest amount, not the most abundant.

L533: Please direct the reader to these data.

L580-584: I suggest to divide into two sentences.

L588-592: This part seems to need additional editing. The dashes seem to indicate that this is from a draft version.

L631: Larger contribution to PBAP in the Arctic?

L641: Where can the reader see this data?

L740: I suggest to include a more recent reference such as Glasius et al., Atmospheric Environment, 173, 127-141 (2018)

L793- : Please provide brief information about what was discussed in Zwaaftink et al. compared to the current study.