Dear authors, after considering your manuscript, the reviews and your answer to the review I asked another reviewer to have a look at your manuscript.

The third reviewers considers your manuscript publishable:

"The paper has some merit because it is one of the first attempts at a difficult problem -- hiding this analysis could result in similar studies making the same mistakes (city-scale fluxes are becoming a hot topic)."

On the other hand, it would require some more work. In particular, there are two issues being mixed: that the modelled emission of Paris can be improved by the inversion and that the measurements on top of the Eiffel tower present a problem. The reviewer means about the measurements on the Eiffel tower::

"I think many of the main reviewer issues are associated with EIF. Do these large mismatches in concentration reflect emission errors or just errors associated with urban heat island vertical mixing processes not captured by the model? Basically, a sensor in the middle of the city is going to require a detailed CFD approach rather than a regular Eulerian model. The authors suggest that interpreting these data will keep modellers busy for many years to come but this does come across as an issue that is being sideswept by the authors. I recommend that they do exactly the opposite and address EIF head on."

This off-hand approach of dealing with the EIF measurements was indeed one of the major concerns of the reviewers and led to a very strong criticism.

Further on the EIF measurements:

"As they are presented I suggest they are an unwanted distraction for everyone, including the reader. I suggest they discuss this site in a separate section or somehow keep it separate from the main analysis. I do however think they could be used to help validate the emission inferred using the other sites using the two methods, making sure the reader is fully aware that this site is unlikely to be described adequately by the model so is not particularly useful. Could they show how representative EIF is to the local region compare the other sites that are situated on the outskirts of Paris?"

I agree with this review and with you that the result, that the EIF measurments present a nuisance, should be published even though there is no solution (except disregarding them) presented. However, I find the manuscript quite hard to read and find it difficult to follow the main argumentation (sure, I am not an expert, which is the reason for asking more reviews than usual). But this seems a bit the core of the problem. Depending on what one expects and considers to be the message of the paper, it leads to rejection or acception.

Kind regards
Mathias Palm

Dear authors, I decided to accept your publication for publication in ACP. Just one very minor issue. Figure 6 is referenced first after reference 7. I think it is better for readability to swap figure 6 and 7. Also from the contents and information of the figures it seems justified.

Mathias