Dear authors,

I appreciate your responses to the reviewer concerns. I find most of your arguments regarding the questions raised by reviewer 2 to be convincing, however I recommend that you add some of that discussion into the actual paper. If this reviewer had those concerns it's likely that other people will too.

More specifically, I am talking about items 1 and 2 in your response to reviewers. For item 1, I think it would be appropriate to add a brief discussion about the potential for non-biological particles to be labeled as fluorescent even with a 9-sigma threshold and your reasoning for why that is unlikely to be a problem here. Similarly, I would also recommend adding text about point 2, regarding the potential effect of using data from two different models of WIBS instruments.

Finally, with regard to item 4 (the issue of the non-specificity of the mass spec markers for biological particles), I can see your point about how the higher threshold, based on the Savage paper, should do a better job of rejecting non-biological things. However, the fraction of particles that you are identifying as biological is very small (generally <1%) and I'm not sure that the graphs in Savage et al., are fully conclusive at that level. Even if HULIS is mostly rejected at the 9-sigma threshold, it seems that just a few misidentified particles could swing your numbers quite a bit and that cluster is just barely above the threshold. Did you check whether those mass spec markers were correlated with dust or biomass emissions? If they are that might indicate that a tiny fraction is bleeding through even at the higher threshold. At a minimum I think a little bit of discussion is warranted.

Anne

Dear Authors,

Thank you for addressing my remaining comments. I am happy to accept your manuscript for publication in ACP.

Anne