CO Editor

Suggestions for revision or reasons for rejection

The authors replied to most of my concerns and revised the manuscript partly according to my comments. The manuscript was improved but there are still some points to be clarified. I comment on their responses one by one as follows:

1. I don't think the 9 sites around downtown can represent the whole Nanjing, but I understand the possible limitation of available observation for this study.

2. Although only PM2.5 observational data is presented in this study, I still suggest you present model simulated changes in both primary and secondary PM2.5 due to emission reduction, which may help explain the weak PM2.5 response (just 9.8%), I also think that discussion about PM2.5 components will make the manuscript to be more comprehensive.

3. How to explain the increase of SO2 concentration (5.1%) although SO2 emission is reduced by 22.1% in August compared with July 2014? what's the meaning of "unpredictable emissions"? based on the difference between the two sensitivity runs, the increasing SO2 concentration with reduction of SO2 emission looks strange, please give more discussion here.

4. " This paper tries to discuss the overall impact of meteorological conditions ...... partial decrease is not that important". I am not satisfied with the response, although SO2, NO2, PM10, PM2.5, CO, and O3 concentrations increased in terms of domain average, there are large areas of concentration decrease for these species, especially for O3, which require a detailed analysis of these changes in response to variations of meteorological variables and chemical reactions (such as temperature, cloud, PBL etc.)

5. The authors corrected errors in Fig. 8 by reruning the model using corrected emission inventory.

6. From the figure 10, a clear impression is emission reduction has little effect on reducing PM2.5 (PM10) level in Nanjing, which appear not to support the conclusion in this manuscript " emission reduction is the dominant factor of the air quality improvement during the YOG". Besides, in fig. 10, the changes due to emission reduction is hardly to see for species other than SO2 and NOx, is it possible to use different scales for the changes from meteorology and emission reduction?

7. It's ok to keep the tables if the authors think they are necessary.

8. The authors clarify the questions.

Interactive discussion

Peer-review completion