Influence of enhanced Asian NO<sub><i>x</i></sub> emissions on ozone in the upper troposphere and lower stratosphere in chemistry&ndash;climate model simulations

Roy, Chaitri; Fadnavis, Suvarna; Müller, Rolf; Ayantika, D. C.; Ploeger, Felix; Rap, Alexandru

doi:https://doi.org/10.5194/acp-17-1297-2017

Articles | Volume 17, issue 2

https://doi.org/10.5194/acp-17-1297-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-17-1297-2017

© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 17, issue 2

Research article

|

27 Jan 2017

Research article |

| 27 Jan 2017

Influence of enhanced Asian NO_x emissions on ozone in the upper troposphere and lower stratosphere in chemistry–climate model simulations

Chaitri Roy, Suvarna Fadnavis, Rolf Müller, D. C. Ayantika, Felix Ploeger, and Alexandru Rap

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Preprint (discussion started on 20 Jul 2016)
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Status: closed

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

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RC1: 'Review on the paper by Roy et al.', Anonymous Referee #2, 28 Jul 2016
- AC1: 'Point to point Answers To Reviewer I comments', S. Fadnavis, 08 Dec 2016
RC2: 'Review Comment on: "Influence of enhanced Asian NOx emissions on ozone in the Upper Troposphere and Lower Stratosphere (UTLS) in chemistry climate model simulations" by Roy et al.', Anonymous Referee #1, 02 Aug 2016
- AC2: 'Point to point Answers To Reviewer II comments', S. Fadnavis, 08 Dec 2016

Peer-review completion

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

AR by Suvarna Fadnavis on behalf of the Authors (08 Dec 2016) Author's response Manuscript

ED: Referee Nomination & Report Request started (12 Dec 2016) by Martin Dameris

RR by Anonymous Referee #2 (13 Dec 2016)

RR by Anonymous Referee #1 (21 Dec 2016)

Suggestions for revision or reasons for rejection

The authors have done considerable work to incorporate the comments of the referees, leading to an improved version of the manuscript.
However, there are still major and minor points that need to be addressed before the paper can be published (see list below).
Additional points mentioned below in comparison to the first referee comment result from the changes of the revised manuscript in comparison to the ACPD version.

Comments to the authors:

Major Comment:

- You write that lightning NOx is included in the simulations, which answers one major point raised by the referees. However, I do not agree with the statement (p.7 l.153-155) that: "Therefore NOx anomalies obtained from the ... do not have an impact of lightning or soil emissions as they are same in all the simulations.". This statement might be true for the soil emissions, if they are simply fed into the model. But for lightning NOx, which I assume is parametrized as in Fadnavis et al 2015, this is not true for a fully-coupled model. A changed circulation (initially due to different anthropogenic NOx emissions) has an effect on convection (raised already in my first comment: General Comments first point) and hence on lightning NOx production. An example of this can be probably seen in Fig.2 d) at the Equator and south of it at ~500-200hPa (blue blob), which is likely connected to less (convective precipitation) in that region (Fig. 9 d). This affects the discussion of the results at various parts in the manuscript.

- With respect to this. Please mention the parametrization scheme of lightning NOx you are using as it is a key aspect of your simulation. Also the content of Table 1 could be stated in the text as it contains mostly repetitive statements. Instead - in my view - a table showing the VOC, CO, NOx emission totals during JJAS (maybe split by sector) over India and China for the CTRL run would be appropriate.

Minor comment:

- Sometimes cross TP transport is indicated with arrows in the Figures, while the differences are really small and might not be important/significant (especially for the Ind38 simulation).

- I was asking for significance of the results in the first comment. Unfortunately, I don't understand the contour lines in Figs. 3 and S6, which are supposed to relate to the 95% confidence levels (using black for the tropopause, as well, is not optimal). I was expecting some transparent shading out of not significant results, or are these contours to various levels. Also have you checked the significance with respect to the other figures? This relates also to the question about cross TP transport.

- On p. 7 l156-159 you mention 4 additional "lightning-off" simulations. However, you only discuss the CTRL "lightning-off" simulation in the whole manuscript. Either only introduce this simulation or make a statement about the other simulations in the manuscript.

- p. 15 l. 356-357: Please include a reference to the Figures that support your statement.

Specific:

- p. 1 l.14: add "emissions" after "(NOx)"

- p 5. l106-108: You state that MLS data was interpolated to potential temperature levels but you are using MLS data on pressure levels (Fig. 1)?

- Sorry about the mistake regarding the MLS kernels, I was thinking about Fig 1b) , i.e. the model data. However, I thought that the MLS AKs are defined for the MLS levels, which do not include 90hPa (https://mls.jpl.nasa.gov/data/ak/MLS-Aura_L2AK-O3-LAT0N_v04-2x_0000d000.txt).

- p. 9 l. 210: "demonstrated" rather than "quantified"?

- p. 10 l 231-235: You attribute the enhanced values of NOx in Fig. 2f to the southern flank of the Himalaya, however, the major sources over China are located east of the Himalaya (Fig. S1)...

- In two Figures the descripition within the graphic and the description in the caption do not match (Figs. 7 and 9).

- Please add the Tibetan Plateau in (one of) the map plots to make the discussion easier to follow. Also, including the outline of the AC in lat/lon vs. height plots, e.g. via winds or just a box, would be helpful to follow some of the statements (e.g. in Sect. 3.3).

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ED: Reconsider after minor revisions (Editor review) (22 Dec 2016) by Martin Dameris

AR by Suvarna Fadnavis on behalf of the Authors (29 Dec 2016) Author's response Manuscript

ED: Publish as is (09 Jan 2017) by Martin Dameris

AR by Suvarna Fadnavis on behalf of the Authors (11 Jan 2017) Manuscript

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Short summary

In the monsoon season, Asian NO_x emissions are rapidly transported to the UTLS and can impact ozone in the UTLS. From chemistry–climate model simulations, we show that increasing Asian NO_x emissions have enhanced ozone radiative forcing over Southeast Asia, which leads to significant warming over the Tibetan Plateau and increase precipitation over India. However, a further increase in NO_x emissions elicited negative precipitation due to reversal of monsoon Hadley circulation.

Influence of enhanced Asian NOx emissions on ozone in the upper troposphere and lower stratosphere in chemistry–climate model simulations

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Interactive discussion

Peer-review completion

Influence of enhanced Asian NO_x emissions on ozone in the upper troposphere and lower stratosphere in chemistry–climate model simulations