Comments on “Land-surface forcing and anthropogenic heat modulate ozone by meteorology: A perspective from the Yangtze River Delta region” by Zhan and Xie

General comments: This manuscript aims to examine the impact of different land cover (LC) data sets and anthropogenic heat on meteorology and air quality as well as on one of the most populated areas in the world. The manuscript is clear and well written.  Despite that, I think this manuscript needs considerable improvement to be considered a novel and meaningful contribution to the existing literature on the subject.

Major issues:

Although the authors discuss in detail the impact of land cover, there are a lot of previous studies which study the impact of land cover datasets on meteorology and air quality. Therefore, this manuscript is just confirming what has been seen in previous papers (I would also like to mention Jiang et al., 2008, Xuemei et al 2009, Park et al., 2014, Fu and Liao, 2014). USGS is an outdated dataset, and the resulting model outputs are somehow expected, as the authors stated in line 427 “Obviously, higher O3 was produced in the MODIS_noAH, indicating that urban expansion will increase surface O3 concentrations.”  Since the authors did not perform a long-term analysis to see the impact of urbanization (MODIS LU) vs pre-urbanization (USGS LU) on meteorology and air quality, but rather a short-term simulation in which they evaluate the model against measurements, I do not see why they are using an obsolete dataset for the present-day simulation. It would be nice to analyze the impact of MODIS vs From-GLC_2015.

On a related note, the changes in predicted ozone are solely driven by changes in meteorology due to the use of different LC datasets. Have the authors considered updating the input MEGAN2 file for their simulation to match the LC data? The distribution of PFTs from the standard MEGAN2 input data are those from 2001. Therefore, the changes in the BVOCs emissions are exclusively influenced by changes in the meteorology since the PFTs remain unchanged throughout the simulations.

Specific comments:

Line 101: “the” instead of “The”

Line 152: delete etc

Line 184: briefly describe how the AH fluxes have been added

Line 217: why are you using 88 hours for spin-up?

Line 238: define adverse weather conditions

Line 251: define Meiyu since the reader might not know the local name of a frontal system

Lines 255-261: It seems that the authors made these statements using only a visual analysis of the data depicted in Fig.4. It would be nice to see the correlation between meteorological variables and MDA8 O3.

Line 300: Have the authors consider using the “topo_wind” option to turn on the surface wind correction?

Figure 7: please use filled dots showing the measurements instead of purple dots if the measurements are available. It is difficult to spot the lines AB, CD, and EF.

Figure 8: Add the modeled PBLH on the plot to sustain the sentence “The maximum O3 production was in the middle of the boundary layer (~800 m) instead of at the surface”

Line 363: “we” instead of “We”

Lines 473-499: Some sentences belong to the introduction, or they are repeating the same information presented in the introduction

Jiang et al., 2008, doi:10.1029/2008JD009820

Xuemei et al. 2009, DOI:10.1007/s00376-009-8001-2

Park et al, 2014, https://doi.org/10.5194/acp-14-7929-2014

Yu and Liao, 2014, https://doi.org/10.3402/tellusb.v66.24987

Comments on “Land-surface forcing and anthropogenic heat modulate ozone by meteorology: A perspective from the Yangtze River Delta region”

       This paper describes the general characteristics of regional O₃ pollution in the Yangtze River Delta (YRD) region, a highly urbanized place with complex geography. The impacts of land-surface forcing and anthropogenic heat (AH) on meteorological factors, local circulations and O₃ are investigated by using the WRF-Chem model. This is an interesting topic to diagnose the changes in local circulations affected by land-surface forcing/AH and their effects on O₃ because these elements are usually at different scales. From this paper, the interactions of these multi-scale local circulations seem to play an important role in O₃ pollution, and this may be an important supplement to current research on related topics. Thus, the manuscript can be considered to be published in ACP after making revisions as follows:

General comments

1. I suggest replacing the “land-surface forcing” in the title as well as the corresponding place in the text with “land use”.
2. Section 3.2.1, since the subsequent results are based on this case, I believe that a more detailed description is needed to make sure the case is in a calm weather. This is an important prerequisite for the formation of local circulations. In fact, plenty of materials, like the time series of meteorological factors, have been given in the section of model evaluation, but should be condensed here.

Specific comments

1. Lines 359-361. The titration of NO does not terminate, and surface O₃ seems to be lowest in the early morning (Figure 6).
2. Lines 395-397. “… the sea-breeze front lifted the boundary layer …”, the development of the boundary layer mainly depends on solar radiation, although some factors do affect the boundary layer height.
3. Figure 7 and 9. O₃ concentration on the lake is higher than that in the city during the day. Why? Will this affect the lakeside cities?
4. Section 3.4.2. Only the sea breeze was discussed in this section. However, both the offshore and onshore flows should be considered when we discuss circulations.
5. Wind arrows in Figure 11 and 14 are too small to identify. Please improve the figure presentations with better quality.

Technical corrections

1. “MODIS_withAH” and “MODIS_AH” should be the same, please choose any one of them.
2. Line 258, “is” -> “are”.
3. Line 277, “provide” -> “provides”.
4. A few typos, grammatical and syntactic mistakes need to be corrected.