The research on new particle formation (NPF) is of great importance considering its vital role in modulating the cloud condensation nuclei. While NPF has been widely studied, the authors primarily focus on the development of aerosol size distribution among different altitudes as well as the impact of aerosol-radiation on NPF. The analysis angle is unique and the manuscript is well written. I have a few comments prior to the acceptance of the manuscript for publication.  

Major comments:

1. A typical NPF figure (dN/dlogDp vs. time) at a few selected altitudes might be helpful for readers to understand the evolution of NPF along with time and altitude.
2. In the abstract, the authors hypothesized that the nucleation processing in the upper boundary layer should be stronger than that at the ground. Since the observational PNSD in the vertical direction is available, I am wondering whether the authors can calculate the formation rate directly. In this way, one can easily identify whether the nucleation processing over the upper altitude is higher than that at the ground.

Minor comments:

Line 120: Some changes were made in the source code of the TUV model so that the model can calculate the J(NO2) and J(O1D) profiles

A bit more information is useful. For instance, a few more words on what major changes have been made.

Line 123: Altitude

Please revise to altitudes

Line 132 (Line 193; 205;304): Transportation

Please revise to transport.

Line 144 for different altitudes and a different time

Please revise to for different altitudes and time

Line 159 These particles were still not well mixed at the range between 0 and 240 m until 11:20.

From Fig. 2, it does not seem to show the mixing at 11:20. Is it something not shown in the figure?

Line 183 (Line 479;295) different times

Please revise to: different time

Line 185: The ratio on the ground surface decreased

It is not clear that the ground decreased compared to ??

Line 196 later

Should be late; if the authors only want to emphasize afternoon, the word "later" should be removed.

Line 266-270

The authors list the altitude of boundary layer height of either 1000 or 500 meters. Please clarify whether these heights are the exact boundary layer heights or approximate altitude? Or they represent a range, i.e., less than 1000 meters?

New particle formation contributes to more than half of CCN and thereby is important for climate. This work conducts the vertical measurements of particle number size distribution based on a moving cabin of 350 m tower. This kind of experiment is interesting and can improve the understanding of the vertical distributions of new particle formation (NPF) in urban environment. However, I believe that the evidences on the occurrence of nucleation at 240 m or upper boundary layer in this manuscript is not enough. A major revision is needed before considering publication in ACP.

Comments:

Line 44-50: It is not suitable to put equations of sulfuric acid proxy and CS and the explanation of these two equations in the Introduction. I suggest moving those to Section 2.

Line 79-89: The time resolutions of instruments need to be presented. How do they compare with the lifting speed of the cabin?

Line119-121: I suggest the author gives the description of the changes of TUV model in SI.

Line 144-145: What are the differences in PNSD when cabin moving upward and downward? Because the time is close when cabin moving upward and downward, I would suppose the PNSDs are similar. If so, I suggest the author merges the upward and downward PNSD. If not, please explain the reasons.

Section 3.2: In this section, the authors discussed the stronger nucleation in the upper boundary layer. However, some more evidences are needed for this conclusion.

1. The maximum altitude of this vertical measurement is 240 m. The boundary layer height is around 1500 m in winter. Therefore, I don’t think this measurement can represent the situations of upper boundary layer even in winter. I suggest the author uses ‘above the urban canopy’ instead of the ‘upper boundary layer’.
2. I suggest the author give the legend of each profile in Fig.3.
3. Are there any ground-based measurements on this day? From the ground-based measurements, is it a new particle formation event day?
4. The ratio of nucleation mode particles number concentrations to Aitken mode particles number concentrations increased at 16:15. Does the author mean the nucleation occur at late afternoon? Most of NPF events start at noontime when the solar radiation is strong. Although the ratio increased at 16:15, the PNSD shown in Fig. 2 is not a typical PNSD of nucleation.
5. Although the wind speed is low during the measurement, the wind direction changed at around 16:00. Is it possible that the change of the air masses caused the observed phenomenon? Are there intensive local anthropogenic emissions to the southwest of measurement site?

Line219-220: The author needs to give some evidences or cite some references here. SO2 can be from the power plant and the NOx is most from the vehicle emissions. They may have different vertical distributions.

Figure 4: The concentration of NOx can be more than 200 ppbv. Is it a heavy pollution day?

Line 243-248: The vertical measurement in this study is from ground level to 240 m. However, in this section the author takes lots of words on the differences between the situations of ground level and the top of boundary layer. From Fig. 5, the [OH] didn’t increase that much at 240 m compared to ground level.

Line 247-254: I don’t think a schematic graph is needed here. Moreover, the schematic graph is not well presenting the author’s view. The loop showing in Fig. 6 is a positive feedback loop, but I think it is not the case in this study.

Section 3.4: In this section, the author discussed the vertical profiles of photolysis rates for 4 types of aerosol profiles. But most of discussions are about the comparisons between the top of boundary layer and ground, which is not related to the measurement of this study. The author also needs to consider the vertical distribution of SO2, CS, VOCs when discussing the reasons of the NPF occurring at high altitude.