A tropical West Pacific OH minimum and implications for stratospheric composition

Rex, M.; Wohltmann, I.; Ridder, T.; Lehmann, R.; Rosenlof, K.; Wennberg, P.; Weisenstein, D.; Notholt, J.; Krüger, K.; Mohr, V.; Tegtmeier, S.

doi:https://doi.org/10.5194/acp-14-4827-2014

Articles | Volume 14, issue 9

https://doi.org/10.5194/acp-14-4827-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue:

The TransBrom Sonne ship campaign in the West Pacific

https://doi.org/10.5194/acp-14-4827-2014

© Author(s) 2014. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 14, issue 9

Research article

| Highlight paper

|

15 May 2014

Research article | Highlight paper |

| 15 May 2014

A tropical West Pacific OH minimum and implications for stratospheric composition

M. Rex, I. Wohltmann, T. Ridder, R. Lehmann, K. Rosenlof, P. Wennberg, D. Weisenstein, J. Notholt, K. Krüger, V. Mohr, and S. Tegtmeier

Download

Final revised paper (published on 15 May 2014)
Preprint (discussion started on 05 Nov 2013)

Interactive discussion

Status: closed

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

- Printer-friendly version

- Supplement

RC C9156: 'Review of Rex et al.', Anonymous Referee #1, 15 Nov 2013
- AC C11726: 'Reply to Reviewer 1', Ingo Wohltmann, 31 Jan 2014
RC C9356: 'Comment on “A Tropical West Pacific OH minimum and implications for stratospheric composition” by M. Rex et al.', Martin Manning, 22 Nov 2013
- AC C11733: 'Reply to Martin Manning', Ingo Wohltmann, 31 Jan 2014
RC C9807: 'Western Pacific OH Minimum', Anonymous Referee #3, 07 Dec 2013
- AC C11740: 'Reply to Reviewer 3', Ingo Wohltmann, 31 Jan 2014

Peer-review completion

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

AR by Ingo Wohltmann on behalf of the Authors (31 Jan 2014) Author's response Manuscript

ED: Referee Nomination & Report Request started (08 Feb 2014) by William Thomas Sturges

RR by Anonymous Referee #1 (19 Feb 2014)

Suggestions for revision or reasons for rejection

This revised paper has now been much improved compared to its original version. It is coherently structured making it easy to follow the presentation of major results and clearly stated conclusions. However, I would have liked a more open discussion of the inherent uncertainties in the authors’ main derivation, i.e., the modelled OH profiles with and without clouds (sections 3, 5.1 and 6). It appears that the temporal variability of water vapour concentrations over the study region (in connection with high reaching convective activity) as well as lack of knowledge on the mechanisms of ozone loss in the Pacific boundary layer form the major physical/chemical uncertainties in the OH simulations. However, the authors should at least provide estimates of inherent uncertainties resulting from the model itself.

Other than that I have only minor comments (see below). The paper makes a significant contribution to our better understanding of global processes linking oceans, atmosphere, and climate change, and therefore should be published.

Minor comments

p. 2, top line: …in clean tropical air… replace with: in clean tropospheric air

p. 2, lines 68-73: These two sentences as written are irritating and appear contradictive. They should be reworded. The first sentence suggests higher Ox and lower H2O levels in the UT, whereas the next sentence points out low Ox due to higher H2O via convection in the UT in reference to (R2).

p.2, line 100: This sentence can be omitted.

p. 3, line 160: It is not clear right away what is meant by background current, i.e., that this is a technical term, unrelated to some atmospheric “current”. I suggest to expand the sentence to: ….based on a correction due to the electrical background current in the ozone sonde measurement cell…

p. 3, Fig. 2, last line and p. 8, line 440: Since OH concentrations are expressed elsewhere in mixing ratios (ppt, which is suitable for this paper), they should also be quoted in ppt on p. 8, and NO levels (detection limit) as well in the Fig. 3 caption.
However, if these were calculated for STP conditions this should be stated explicitly.

p. 3, lines 183/184: Correct to: …just missed…, but the results agree well…

p. 4, line 227 and Fig. 4a caption: The symbols are not dots, but open circles. Also, I suggest to choose a different line colour for the circles, such as yellow, for better viewing.

p. 4, line 283: Omit: “large” uncertainty with respect to Tan et al.’s OH measurements or even better (as pointed out above) add a quantitative comparison here of uncertainties in the measured vs. the present calculated OH concentrations !

p. 5, line 372 and Fig. 4h: The meaning of Fig. 4h is not clear. The % per day y-axis label needs to be explained. In addition it should be stated if both photolysis and OH reactions have been considered. Furthermore, the relatively long tropospheric residence times of several tens of days are, at first glance, surprising. Some discussion to illustrate the plausibility of this range would be helpful.

p. 8: It should be clearly stated whether the calculated OH concentrations represent 24 hour averages or daytime averages (with the model assuming zero OH levels at night).

Referee Report: PDF

Hide

ED: Reconsider after minor revisions (Editor review) (19 Feb 2014) by William Thomas Sturges

AR by Ingo Wohltmann on behalf of the Authors (21 Feb 2014) Author's response Manuscript

ED: Reconsider after minor revisions (Editor review) (11 Mar 2014) by William Thomas Sturges

AR by Ingo Wohltmann on behalf of the Authors (26 Mar 2014) Author's response Manuscript

ED: Publish as is (27 Mar 2014) by William Thomas Sturges

AR by Ingo Wohltmann on behalf of the Authors (27 Mar 2014)