Monitoring the compliance of sailing ships with fuel sulfur content regulations using unmanned aerial vehicle (UAV) measurements of ship emissions in open water

Zhou, Fan; Hou, Liwei; Zhong, Rui; Chen, Wei; Ni, Xunpeng; Pan, Shengda; Zhao, Ming; An, Bowen

doi:https://doi.org/10.5194/amt-13-4899-2020

Articles | Volume 13, issue 9

https://doi.org/10.5194/amt-13-4899-2020

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

https://doi.org/10.5194/amt-13-4899-2020

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

Articles | Volume 13, issue 9

Research article

|

17 Sep 2020

Research article |

| 17 Sep 2020

Monitoring the compliance of sailing ships with fuel sulfur content regulations using unmanned aerial vehicle (UAV) measurements of ship emissions in open water

Fan Zhou, Liwei Hou, Rui Zhong, Wei Chen, Xunpeng Ni, Shengda Pan, Ming Zhao, and Bowen An

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Final revised paper (published on 17 Sep 2020)
Preprint (discussion started on 05 Mar 2020)

Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Sulphur compliance monitoring', J. Duyzer, 26 Mar 2020
- AC1: 'Answer to Referee #1', Fan Zhou, 19 Jun 2020
RC2: 'Review of Zhou et al., 2020', Anonymous Referee #2, 14 May 2020
- AC3: 'Answer to Referee #2', Fan Zhou, 19 Jun 2020
AC2: 'Answer to Referee #2', Fan Zhou, 19 Jun 2020

Peer-review completion

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

AR by Fan Zhou on behalf of the Authors (19 Jun 2020) Author's response Manuscript

ED: Referee Nomination & Report Request started (22 Jun 2020) by Andreas Richter

RR by Anonymous Referee #2 (23 Jul 2020)

ED: Publish subject to minor revisions (review by editor) (24 Jul 2020) by Andreas Richter

Dear Fan Zhou,

I have now received a positive report from Referee #2. before accepting your manuscript for publication, I have some comemnts and suggestions as well as some requests for revisions:

As pointed out by one of the reviewers, there is a clear difference in the time constant of the SO2 and CO2 sensors. This is less visible in the revised manuscript as you changed the scale but this is something that you need to address. From what I see in your original graphs, the SO2 instrument has a much shorter time constant and thus shows more variability and a time shift compared the CO2 instrument. This is of course a problem when computing FSC if the measurement time in the centre of the plume is short. In such conditions, the SO2 peak will be larger than the corresponding peak in CO2 and the FSC will be overestimated. I think the proper approach would be to either take averages long enough to make sure that the full signal is taken by both instruments (30 seconds) or to numerically degrade the SO2 time series to correspond to the time constant of the CO2 instrument.

A related question is, whether you have used exactly the same time for the readings of the maximum values of SO2 and CO2, although there is an obvious time shift between the two.

One of the reviewers pointed out several important issues which could affect the accuracy of the measurements, including cross sensitivity to NO2, the impact of large temperature changes in the exhaust plume and the issues of water vapour and particle contamination of the instruments. Please add a short discussion of these points to the section on uncertainties.

In Figure 5, highlight the points used for the FSC computation.

In Figure 6, please indicate by a dotted vertical line the FSC limit of 0.5%.

Quantification of poor measurements: Why don’t you use the correlation between SO2 and CO2 time series to determine the quality of a measurement? In my opinion, this should be a good first guess of which measurements to use and which to discard.

Best regards,

Andreas Richter

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AR by Fan Zhou on behalf of the Authors (02 Aug 2020) Author's response Manuscript

ED: Publish as is (06 Aug 2020) by Andreas Richter

AR by Fan Zhou on behalf of the Authors (07 Aug 2020)

Short summary

On 15 July 2019, using an unmanned aerial vehicle (UAV), maritime authorities ferreted out a sailing ship whose fuel sulfur content (FSC) failed to meet Chinese regulations. This was the first time that a sailing ship had been caught for having failed the FSC regulations in China. The UAV system, method, and monitoring result utilized are discussed in this paper. We recommend that emissions from sailing ships be monitored more often in the open water in the future.