Dear Qindan Zhu,

as you will have seen, both reviewers have submitted their reports on your revised manuscript and made detailed suggestions for (minor) revisions needed before the paper can be accepted. Please consider them and change your manuscript accordingly.

In addition, as already mentioned when accepting your original manuscript for ACPD, I have some questions about the comparison to OMI data:

• In Figure 3, is the cloud fraction threshold of 0.2 used as in Figure 4? If so, please add this information to the caption

• On page 10, line 2, you cite Laughner et al., 2019 for the statement that “uncertainty due to AMF calculation for BEHR v3.0B is smaller than 30%“ I couldn’t find the corresponding statement in that paper and think that more qualification is needed – which parts of the uncertainty do you consider in this number? The way this number is used suggests that you exclude uncertainty from the vertical profile used?

• Why is it OK to assume that AMF uncertainties (which are strongly related to knowledge of surface reflection) are reduced like a random uncertainty when averaging?

• In order to better understand the reason for the large changes over urban areas when changing the lightning parametrisation it would be good to add figures showing

o Vertical profiles of NO2 for the three cases of no lightning, old parametrisation and new parametrisation as well as the scattering weights

o For the two cases of August 24 and September 10 that you discuss

• Please change the labels in Fig. 4 from “change in” to “difference in”

• Please check again if the figures really show BEHR – WRF-Chem as stated in the text and in the caption. Judging from the numbers, I would guess that in fact WRF-Chem – BEHR is shown.

• Why is the spatial pattern of lightning (Fig. 1d) not reflected in Figure 4a?

Please include a point by point reply to the suggestions made by the reviewers and my questions on the AMFs when submitting the revised (and hopefully final) version of your manuscript.

Best regards,

Andreas Richter

Dear Qindan Zhu,

thank you for your revised manuscript "Lightning NO2 simulation over the Contiguous US and its effects on satellite NO2 retrievals" which I'm glad to accept for publication in ACP subject to technical corrections.

Please check the first paragraph of the conclusions:

"...and find that the switch of convective scheme reproduces day-to-day variation ..." - it's not the switch that reproduces variations but rather the model which reproduces variation after switching the convective scheme

I think it would also be worthwhile to state somewhere in the text or at the new figure S4 that from your work, there is (at least in my understanding) no indication that lightning NO2 has a significant impact on the AMF at the time and location you are investigating. In your conclusions, you state that "This study emphasizes the importance of including reliable lightning NO2 in a priori profiles for satellite retrievals" but the way I see it, just switching off lightning in the model would probably lead to AMF values comparable to those you determined with the updated version of the model. This is why I suggested to include the NO2 model without lightning in Fig. S4, just to demonstrate that lightning (if modelled correctly) is not relevant here.

Best regards,

Andreas Richter