Referee #1
I have three questions about the manuscript.

1. The comparison of simulated and observed O3-T relationship for five cities is not done properly （Line 187； Fig S1). The authors derived the O3-T slope from daily data in all five cities in the scatter plot (Fig. S1). Thus derived slope may be determined mainly by the "systematic" differences among the five cities. Indeed, Fig.3 and Fig. 7 shows the local O3-T slope over most regions of China is smaller than 1 ppb/K, inconsistent with the CMAQ slope shown in Fig. S1 and Line 187 （2.4 ppb/K).

2. I find Section 3.3 and Fig. 8 and 9 redundant. The spatial distributions are essentially the same between Fig. 3 and Fig. 8, and between Fig. 4 and Fig. 9. I do not see the point of these figures and corresponding discussions.

3. There is ambugity regarding how the authors perturbed the meteorological parameters. It is not clear to readers what processes are affected by the perturbation.

For example, when the authors perturb T in CMAQ, does absolute humidity or relative humidity change? For relationship between T, AH, and RH to be invalid, one of them has to change. But changing AH or RH can have different consequences on chemical reactions. (e.g., smaller RH can cause less aerosol water and thus impact on the SNA). Or, maybe the only thing considered is T in the chemical kinetic computation?

Similar case for PBLH. When authors claim they perturbed PBLH in CMAQ, it is most likely that they simply perturbed the PBLH parameter in the model's boundary layer mixing scheme. But a real life change in PBLH will also implicate changes in vertical profiles in T, WS, AH, etc.

Minor comments:
Line 37: -1 ug m-3 %-1
Fig. 4: caption for y axis is wrong


Referee #1
I have a suggestion for the authors if they can include it will further bolster their manuscript.
The authors claim that they “isolate the effects of individual meteorological parameters” however the met parameters are inter-linked e.g. Change in temperature will result in corresponding change of PBL height, In that case how can the authors claim that they only study the isolated effect of change in temperature in this case. Is such an isolated change of a meteorological parameter possible meaning say only change of temperature without change in PBL? If not then your result from the study that “July O3 in Beijing is very sensitive to temperature and not to PBL and hence additional emission controls would be needed if temperature is predicted to increase in future” which is entirely based on presumption that either PBL or temperature will change might not give correct information. I suggest the authors can describe some uncertainties about their statement.