Dear authors,

Thank you for submitting your revised manuscript and author final responses. You have addressed the issues raised by the referees. However, the manuscript can be further improved by additional revisions.

I have a number of comments for your consideration in the revision.

1) Throughout the manuscript phrases like "polluted air mass", "air pollution episodes", "air pollution transport", etc. are used. However, the Nam CO site and the vast TP are in fact a very clean in terms of aerosol pollution, as shown by your measurements (PM1 averaged 2 ug/m3). I understand that you are differentiating air masses slightly influenced by pollution transport from those representing background. Nevertheless, I suggest choosing suitable words and expressions to avoid misunderstanding.

2) Line 66: change "Westliers" to "westerlies".

3) Lines 87-89: "The ambient conditions at high elevation regions are characterized by higher solar radiation and concentrations of oxidants such as OH radicals and O3, which makes photochemical processing in this high elevation remote region intense and likely dominant." Are there any references? Particularly for OH that has been much less observed at high-elevation sites. "OH radicals" should be changed to "OH" or "OH radical".

4) Line 123: "county" is a concept of administrative district, but I think here you are meaning a residence location. If so, a better word is "village" or "town". You can also give a population number as additional information.

5) Lines 124-125: "A freeway for tourists was built about 5 km south of the station." It is better to give estimated traffic intensity as this may be highly relevant to your measurements.

6) Lines 137-144: these two sentences need to be reworded. It is not clear if all the instruments named here were taking samples from the single inlet. Nor the total flowrate (16L/min or 10L/min?). An inlet cannot be maintained by a vacuum pump, but the air flow through the inlet can. What is the common abbreviation for high-resolution time-of-flight aerosol mass spectrometer? HR-AMS or HR-ToF-AMS?

7) Although a number of instruments were deployed at the site, only small part of the data (PM1 components and BC) are presented and discussed in this paper. I suggest deleting or simplifying the description of instruments, from which no measurements are used in the current paper.

8) Line 168: "calibrated" using what?

9) Line 210: change "India monsoon" to "South Asian monsoon".

10) Lines 257-259: "The slope was ~0.75 during P2 (Figure S5a), which suggested that there was excess ammonium to neutralize sulfate and nitrate." The slope 0.75 suggests that all sulfate and nitrate were neutralized by ammonium and there was additional ammonium, which indicates the presence of acids other than sulfuric and nitric acids in aerosol. I would suggest changing this sentence to "The slope was ~0.75 during P2 (green circles, Figure S5a), which suggests that there was more ammonium than needed to neutralize sulfate and nitrate."

11) Line 274: "plateau monsoon" is a less used concept. If it is really important in the context of your nighttime-daytime differences, a little detailed explanation is needed to show how the plateau monsoon caused the observed phenomena. In addition, the Nam Co site is very close to the Nyainqentanglha Mountains, which may cause mountain-valley (plain) breeze. Did this play a role in your measurements?

12) Lines 313-314: "The decreased mass concentration of BC indicated no primary aerosol transportation, ..." needs revision. BC is primary aerosol but primary aerosol contains not only BC. Moreover, decreased mass concentration of BC does not mean the absence of BC.

13) Lines 324-328: Some of the paired averages are very close to each other. You need to take significance tests to show whether or not they are statistically significant different.

14) Line 335: change "could relate with" to "could be related with".

15) Line 349-350: "Thus the enhanced aerosol concentrations during afternoon could be possibly attributed to the mixed downward of aerosol layer at 16 – 18 km altitude during the growth of TP boundary layer. This type of transportation could not be captured by re-analysis of data used in the back-trajectory analysis likely due to the low time and spatial resolution." I think these are too speculative! I do not exclude the possibility that air from 16-18 km altitudes is mixed downward to the site (~4.7 km) in some particular events. However, you are discussing average conditions. Some small-scale activities may not be visible in the reanalysis data but a greater than 10 km of vertical motion of air mass may horizontally extend over meso-scale. Even if you cannot test your hypothesis using the reanalysis data, the ozone and RH measurements available from your site may be used to investigate the impact of air mass from the upper troposphere and low stratosphere, and the WRF model should be a suitable tool as well for this purpose.

16) Lines 359-362: I would change this sentence to "C4H9+ was a minor peak in the OA spectra (0.6% of the total signal) and its organic-equivalent concentration averaged only 0.008 μg m-3 during this study, suggesting a minimal contribution from traffic-related primary OA". Figure 5 does not show any data of C4H9+.

17) Line 383: remove "totally". They are not totally different particularly in the data for P2 and Mon (Figure 6).

18) Line 384: I do not think you have robust evidence for South Asia origin of MO-OOA. You may be able to test your statement by comparing trajectories associated with high MO-OOA with those associated with high LO-OOA.

19) Lines 421-422: "During 8-11 June, there was a weak ridge system over the north. Intensified wind from north was observed as illustrated by HYSPLIT results (Figure 5b) ... " this is contradictory to "The possible reason was that the weak trough during P2 intensified the wind from west other than south where a lot of biomass burning emission sources locate (Figure 5b). " (Lines 426-428). The period 8-11 June was a part of P2. What was the synoptic system? Weak ridge or weak through? And which wind direction prevailed? North or west? Figure S9 shows that the wind was weak westerly and weak southerly during 8-11 June. Figure 5b is a wrong reference in both sentences. No HYSPLIT results and biomass burning data are shown in Figure 5.

20) Line 428: "low-cut" should be "cut-off low" and the cut-off lows occur in the troposphere. Zhang et al. (2017) show geopotential height fields at 300 hPa, which is in the upper troposphere.

21) Line 442: "our findings have implications for aerosol deposition ..." or "our measurements can be used for estimating aerosol deposition ...".

22) Line 732: change "mountain sites" to "high elevation sites". Nam Co is not a mountain site.

23) Figure 2: X-axis label is cut. Many figures look too busy.

24) Figure 3: No details about trajectories. How many days? Ending height？Which reanalysis dataset was used? Url for fire spot data should be given.

25) Figure 4: Chaotic use of colors and symbols.

26) Figure 7: Partly cut y-axis labels. Incomplete second y-axis label (c).

27) Figure 9: Poor color/symbol contrast.

28) Figure 10: Too busy and lack of descriptions in figure caption.

29) Figure 12: Poor color contrast for MO- and LO-OOA. What are the dashed lines in (c)?

Sincerely,

Xiaobin Xu

Dear authors,
I am pleased to inform you that your paper is accepted for publication in ACP. Congratulaions! Thank you for your contribution to ACP/AMT inter-journal special issue SOAR-TP.
Sincerely,
Xiaobin Xu