NO<sub><i>x</i></sub> emission estimates during the 2014 Youth Olympic Games in Nanjing

Ding, J.; van der A, R. J.; Mijling, B.; Levelt, P. F.; Hao, N.

doi:https://doi.org/10.5194/acp-15-9399-2015

Articles | Volume 15, issue 16

https://doi.org/10.5194/acp-15-9399-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Special issue:

East Asia emissions assessment (EA2)

https://doi.org/10.5194/acp-15-9399-2015

© Author(s) 2015. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 15, issue 16

Research article

|

24 Aug 2015

Research article |

| 24 Aug 2015

NO_x emission estimates during the 2014 Youth Olympic Games in Nanjing

J. Ding, R. J. van der A, B. Mijling, P. F. Levelt, and N. Hao

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Final revised paper (published on 24 Aug 2015)
Supplement to the final revised paper
Preprint (discussion started on 04 Mar 2015)

Interactive discussion

Status: closed

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

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- Supplement

RC C1595: 'Review of Ding et al. “NOx emission estimates during the 2014 Youth Olympic Games in Nanjing”, ACPD, 2015', Anonymous Referee #1, 15 Apr 2015
- AC C3373: 'Reply to reviewer #1', Jieying Ding, 09 Jun 2015
RC C1615: 'Review of Ding et al. (2015)', Anonymous Referee #2, 16 Apr 2015
- AC C3374: 'Reply to reviewer #2', Jieying Ding, 09 Jun 2015
RC C1646: 'review', Anonymous Referee #3, 17 Apr 2015
- AC C3375: 'Reply to reviewer #3', Jieying Ding, 09 Jun 2015
RC C1665: 'Review', Anonymous Referee #4, 17 Apr 2015
- AC C3376: 'Reply to reviewer #4', Jieying Ding, 09 Jun 2015

Peer-review completion

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

AR by Jieying Ding on behalf of the Authors (09 Jun 2015) Author's response Manuscript

ED: Referee Nomination & Report Request started (20 Jun 2015) by Gregory Frost

RR by Anonymous Referee #3 (29 Jun 2015)

RR by Anonymous Referee #2 (13 Jul 2015)

Suggestions for revision or reasons for rejection

Thank you to the authors for carefully addressing all reviewer comments. However, I have to insist that they weaken their conclusions regarding emission reductions being caused by local legislation.

Specifically,

- p.1/l.25 should say something like "probably indicates that ..."

- p.14/l.20 has to be weakened; the current statement "Due to the effect of the continuous air quality regulations" is not backed by the authors' analysis. Maybe, a "probably" could be inserted at the beginning of this sentence.

- p.16/l.19 again states in certainty a causal relation between policy measures and NOx emission reductions. This has to be weakened, perhaps by adding "possibly": ", possibly showing that the air quality measures ..."

Furthermore, the following issues have to be addressed before accepting this manuscript for publication in ACP:

- p.8/l.31 The authors should copy the exact formula/table they use to convert AQI to NOx from their reference so that this is available to non-Chinese community. This could be done in a supplement.

- p.10/l.22 The authors insist that using a 8month average of in-situ measurements allows them to judge the quality of the CTM simulations, in spite of studies they cite themselves. However, while using a long temporal average might average out any random fluctuations, but the spatial misrepresentation of a single point in-situ measurement compared to the large model grid cell cannot be corrected for using temporal averaging.

- The authors should give the details for the injection height for each of the emission sectors, possibly in a supplement (see p.9/l.11 of the authors' response to the reviewer comments).

- Given the authors' response to reviewer comments, p. 9/l. 29ff, doesn't this mean that DECSO favours emission increases over emission reductions? Maybe this could be added to p.7/l.2 of the revised manuscript.

- In p.21/l.3 of the authors' response, they write of "a large range of media, newspaper and internet sources". It would be good if all these sources could be properly cited, perhaps in a supplementary document

- In p.23/l.16 of the authors' response, the authors say that their Kalman filter technique used by DECSO does not consider a time lag in the emission errors. This has to be explicitly mentioned in the manuscript in the discussion of Figure 10.

- In several places in the authors' response to the reviewer comments, they explain that the NOx emission reductions come from continuous AQ regulation which remains in effect also after the end of the YOG. However, in Table 1, only traffic-related emission control measures are marked as "permanent". Does this mean that the observed reduction comes mostly from the transportation/traffic sector? The authors should discuss this in the manuscript.

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RR by Anonymous Referee #1 (14 Jul 2015)

Suggestions for revision or reasons for rejection

Review #2 of resubmitted Ding et al., 2015, ACPD

General comments:

I found the resubmitted paper much easier to read, and several of my comments were addressed in sufficient detail. The intro, method description, etc are quite good now. I still feel like the conclusions are not terribly definitive and there are questions raised by the results that are hard to answer, but the authors seem to do a pretty thorough job in the analysis and making use of available data.

There is obviously a significant decline in emissions in September 2014, and this is attributed to remaining controls leftover from the Games. I don't understand why the emissions would go back up in October 2014. Is there an explanation for this?

Specific comments:

In many cases, the authors use the expressions “with XX%”. Usually the correct English phrasing is “by XX%”.

Page 3, line 32: Same comment as my previous review: Change “concentration” to “column”.

Page 5, line 25: I still think this partitioning of industry sector needs justification, other than gut feeling.

Page 8, line 19: How is this concluded if you had no observations before? How do you get a 37% increase over zero observations? Also, on page 16, line 12 you blame lack of observations. It is still not clear to me how many observations you have. One, ten, hundreds? This is significant for your conclusions.

Page 9, line 5: You don't have to include this in the final paper, but curious if you tried emailing sources in China? Surely someone must know where this monitor is located!

Page 10, line 23: Usually “noise” is used to discuss instrument measurement noise. I think you mean transient influences here.

Page 14, line 1: Again, this statement discards data because it does not meet a hypothesis which hasn't even been found to be correct yet. Reword.

Page 15, line 18: If the NOx emissions are so dependent on air conditioning, might be helpful to include a sentence on the temperatures during summer 2013/2014 to convince reader this can be disentangled from the patterns you see. Was September 2014 particularly cold for example?

Page 17, line 18: I'm not very familiar with Kalman filter data assimilation. Why don't you get larger error bars if there are few observations to assimilate in August 2014?

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ED: Reconsider after minor revisions (Editor review) (23 Jul 2015) by Gregory Frost

AR by Jieying Ding on behalf of the Authors (31 Jul 2015) Author's response Manuscript

ED: Publish as is (12 Aug 2015) by Gregory Frost

AR by Jieying Ding on behalf of the Authors (17 Aug 2015)

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Short summary

We derived the NOx emissions from the OMI satellite observations. We find a NOx emission reduction of at least 25% during the Youth Olympic Games in Nanjing in 2014. The emission estimate algorithm has detected an emission reduction of 10% during the Chinese Spring Festival. This paper also shows that the observed concentrations and the derived emissions from space have different patterns that provide complimentary information.

NOx emission estimates during the 2014 Youth Olympic Games in Nanjing

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Interactive discussion

Peer-review completion

NO_x emission estimates during the 2014 Youth Olympic Games in Nanjing