MAX-DOAS measurements of NO<sub>2</sub>, SO<sub>2</sub>, HCHO, and BrO at the Mt. Waliguan WMO GAW global baseline station in the Tibetan Plateau

Ma, Jianzhong; Dörner, Steffen; Donner, Sebastian; Jin, Junli; Cheng, Siyang; Guo, Junrang; Zhang, Zhanfeng; Wang, Jianqiong; Liu, Peng; Zhang, Guoqing; Pukite, Janis; Lampel, Johannes; Wagner, Thomas

doi:https://doi.org/10.5194/acp-20-6973-2020

Articles | Volume 20, issue 11

https://doi.org/10.5194/acp-20-6973-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Special issue:

Study of ozone, aerosols and radiation over the Tibetan Plateau...

https://doi.org/10.5194/acp-20-6973-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Articles | Volume 20, issue 11

Research article

|

12 Jun 2020

Research article |

| 12 Jun 2020

MAX-DOAS measurements of NO₂, SO₂, HCHO, and BrO at the Mt. Waliguan WMO GAW global baseline station in the Tibetan Plateau

Jianzhong Ma, Steffen Dörner, Sebastian Donner, Junli Jin, Siyang Cheng, Junrang Guo, Zhanfeng Zhang, Jianqiong Wang, Peng Liu, Guoqing Zhang, Janis Pukite, Johannes Lampel, and Thomas Wagner

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Final revised paper (published on 12 Jun 2020)
Supplement to the final revised paper
Preprint (discussion started on 21 Jan 2020)

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Status: closed

AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment

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- Supplement

RC1: 'MAX-DOAS measurements of NO2, SO2n HCHO and BrO at Mt Wliguan WMO/GAW global baseline station in the Tibetan Plateau', Anonymous Referee #1, 12 Feb 2020
- AC1: 'Authors' Relpy to Anonymous Referee #1', Jianzhong Ma, 01 Apr 2020
RC2: 'Review', Anonymous Referee #2, 28 Feb 2020
- AC2: 'Authors' Reply to Anonymous Referee #2', Jianzhong Ma, 01 Apr 2020

Peer-review completion

AR: Author's response | RR: Referee report | ED: Editor decision

AR by Jianzhong Ma on behalf of the Authors (01 Apr 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (03 Apr 2020) by Tao Wang

RR by Anonymous Referee #2 (22 Apr 2020)

Suggestions for revision or reasons for rejection

In their revised version, the authors have moved a lot of material into the supplement making the main article much more accessible for readers. They have also added a comparison of their measurements with previous observations at the same site and high altitude site observations from other stations reported in the literature. This provides context to the results which has been missing in the original manuscript.

Unfortunately, no attempt was made to add some interpretation or scientific questions to be answered which would have made this a much more valuable study.

There are still three points from my original review which I think the authors need to address:

1) The authors added interesting figures on 2d-RTM calculations but do not at all explain or discuss them in the text. A dedicated section needs to be added to the text as promised in the reply to my review.

2) While it is good to hear that the authors trust their pointing correction to be accurate within 0.5 degrees, this information should be added to the article and some kind of uncertainty estimate needs to be added to the mixing ratios derived, including the effect from pointing uncertainty.

3) There was a misunderstanding with respect to my question about the enhanced mixing ratios. The authors now changed the sentence in the conclusions to

"For NO2 and HCHO higher dSCDs are found for lower elevation angles than for higher elevation angles, indicating enhanced trace gas mixing ratios in the lower troposphere over WL"

First of all, this still does not answer die question of relative to what the mixing ratios are enhanced (a climatology? other altitudes? expectations?).

In addition, the sentence now is in my opinion not strictly correct - lower elevation angles have longer light paths and therefore usually larger dSCDs. Whether or not this indicates larger trace gas mixing ratios at a certain altitude can only be determined by some kind of profile inversion algorithm. In the opposite situation (smaller dSCDs at low angles), the situation is clearer as discussed for BrO.

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ED: Publish subject to minor revisions (review by editor) (24 Apr 2020) by Tao Wang

AR by Jianzhong Ma on behalf of the Authors (09 May 2020) Author's response Manuscript

ED: Publish as is (13 May 2020) by Tao Wang

AR by Jianzhong Ma on behalf of the Authors (15 May 2020) Manuscript

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Short summary

We made ground-based MAX-DOAS measurements at the Mt. Waliguan WMO GAW global baseline station (WLG) in the Tibetan Plateau during the years 2012–2015. We retrieve the differential slant column densities (dSCDs) of NO₂, SO₂, HCHO, and BrO from measured spectra at different elevation angles. Mixing ratios of these trace gases in the background troposphere over WLG are derived based on these dSCDs at a 1° elevation angle and the TRACY-2 radiative transfer model simulations.

MAX-DOAS measurements of NO2, SO2, HCHO, and BrO at the Mt. Waliguan WMO GAW global baseline station in the Tibetan Plateau

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MAX-DOAS measurements of NO₂, SO₂, HCHO, and BrO at the Mt. Waliguan WMO GAW global baseline station in the Tibetan Plateau