Dear Jianfeng Li,

I’m pleased to accept your revised manuscript "Inferring the anthropogenic NOx emission trend over the United States during 2003–2017 from satellite observations: Was there a flattening of the emission trend after the Great Recession?" for publication in ACP subject to minor revisions.

Most of the points raised by the reviewers have been answered and addressed in the revised version, but I have some additional comments and suggestions listed below. Please consider them carefully and provide a point by point reply together with the revised final manuscript.

Best regards,

Andreas Richter

• In my opinion, a weakness of this work is the lack of separation between chemical and other factors resulting in non-linearities. In the manuscript, chemical non-linearities are often mentioned but they probably play only a minor role compared to the main factor, the relative contribution of anthropogenic to total NOx emissions in a given grid cell. If that’s possible, it would therefore be good to add some information on which fraction of the observed non-linearity is really due to chemical non-linearities.

• Abstract, line 17: “non-linearity in the emission-TVCD relationship” should be “anthropogenic emission”

• Introduction, line 31: “unfavourable to climate change” – please rephrase

• Introduction, line 35: now soil emissions are mentioned specifically making the statement more correct but highlighting that these numbers without an estimate for lightning NOx are incomplete. Please add an estimate for lightning.

• Line 64: paragraph starts with chemical non-linearities, suggesting that the following discussion is about chemistry while I would argue that most of the following observations are explained by the relative contribution of anthropogenic emissions, not chemical non-linearities.

• Line 84: again, chemical non-linearity is mentioned explicitely but I find this misleading.

• Line 204: “in part” – are there any other possible reasons for the non-linearity?

• Line 251: I can’t really see the difference in variability between the two overpass times…

• Line 256: … and even if it were present, why is that indicative of chemical non-linearity?