Evaluating Sentinel-5P TROPOMI tropospheric NO<sub>2</sub> column densities with airborne and Pandora spectrometers near New York City and Long Island Sound

Judd, Laura M.; Al-Saadi, Jassim A.; Szykman, James J.; Valin, Lukas C.; Janz, Scott J.; Kowalewski, Matthew G.; Eskes, Henk J.; Veefkind, J. Pepijn; Cede, Alexander; Mueller, Moritz; Gebetsberger, Manuel; Swap, Robert; Pierce, R. Bradley; Nowlan, Caroline R.; Abad, Gonzalo González; Nehrir, Amin; Williams, David

doi:https://doi.org/10.5194/amt-13-6113-2020

Articles | Volume 13, issue 11

https://doi.org/10.5194/amt-13-6113-2020

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

Special issue:

TROPOMI on Sentinel-5 Precursor: first year in operation (AMT/ACP...

https://doi.org/10.5194/amt-13-6113-2020

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

Articles | Volume 13, issue 11

Research article

|

17 Nov 2020

Research article |

| 17 Nov 2020

Evaluating Sentinel-5P TROPOMI tropospheric NO₂ column densities with airborne and Pandora spectrometers near New York City and Long Island Sound

Laura M. Judd, Jassim A. Al-Saadi, James J. Szykman, Lukas C. Valin, Scott J. Janz, Matthew G. Kowalewski, Henk J. Eskes, J. Pepijn Veefkind, Alexander Cede, Moritz Mueller, Manuel Gebetsberger, Robert Swap, R. Bradley Pierce, Caroline R. Nowlan, Gonzalo González Abad, Amin Nehrir, and David Williams

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Final revised paper (published on 17 Nov 2020)
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Preprint (discussion started on 25 May 2020)
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Interactive discussion

Status: closed

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

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- Supplement

RC1: 'Referee Comments', Anonymous Referee #3, 17 Jun 2020
- AC1: 'Response to RC1', Laura M. Judd, 13 Aug 2020
RC2: 'Review', Anonymous Referee #1, 18 Jun 2020
- AC3: 'Response to RC2', Laura M. Judd, 15 Aug 2020
  - AC4: 'Small correction to my RC2 response', Laura M. Judd, 16 Aug 2020
RC3: 'Review', Anonymous Referee #2, 19 Jun 2020
- AC2: 'Response to RC3', Laura M. Judd, 13 Aug 2020

Peer-review completion

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

AR by Laura M. Judd on behalf of the Authors (16 Aug 2020) Author's response Manuscript

ED: Publish subject to minor revisions (review by editor) (29 Sep 2020) by Steffen Beirle

Dear Laura Judd,
congratulations to this extensive, thorough and well-designed work on evaluating the TROPOMI NO2 product with airborne and Pandora measurements.

Before final publication, I would like to ask you to deal with the following issues:

1. There is a special issue on TROPOMI (joint AMT/ACP):
https://amt.copernicus.org/articles/special_issue1002.html
You might consider asking Copernicus whether your study could be added to this special issue in order to increase visibility; I don't know if it is still possible, but it might be worth trying.

2. The TROPOMI NO2 algorithms have been improved over the last months. It will take some time until all data can be reprocessed, but it might be very interesting to check the comparisons of the reprocessed data with the existing airborne/Pandora measurements in future.
I hope that your dataflow is largely automatized so that such an update would be possible without much effort.
It might be worth mentioning this aspect as outlook in the conclusions.

3. As far as I understood, the problem with CTH occurs where the assumend surface albedo is wrong (as a consequence of the coarse resolution of the albedo map).
I would appreciate if this aspect could be specified when mentioning the CTH issue in abstract and conclusions.

4. I have been contacted by the Editor of the paper
https://amt.copernicus.org/preprints/amt-2020-148/
which also deals with TROPOMI validation with airborne measurements and also claimed to be the "first study" doing this in the initial submission.
In public discussion, the authors have been asked to add a reference to your study and to soften the statement on being the first study.
The authors have agreed to do this, but have asked their Editor to contact me and ask you the same.
Since both studies have been submitted almost concurrently, I agree that it would be adequate if you would
(a) add a reference to Tack et al., 2020, and
(b) soften the statements on being the first study using airborne data for TROPOMI validation accordingly.

Kind regards,

Steffen Beirle

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AR by Laura M. Judd on behalf of the Authors (29 Sep 2020) Author's response Manuscript

ED: Publish as is (02 Oct 2020) by Steffen Beirle

AR by Laura M. Judd on behalf of the Authors (02 Oct 2020) Manuscript

Post-review adjustments

AA: Author's adjustment | EA: Editor approval

AA by Laura M. Judd on behalf of the Authors (13 Nov 2020) Author's adjustment Manuscript

EA: Adjustments approved (13 Nov 2020) by Steffen Beirle

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Short summary

This paper evaluates Sentinel-5P TROPOMI v1.2 NO₂ tropospheric columns over New York City using data from airborne mapping spectrometers and a network of ground-based spectrometers (Pandora) collected in 2018. These evaluations consider impacts due to cloud parameters, a priori profile assumptions, and spatial and temporal variability. Overall, TROPOMI tropospheric NO₂ columns appear to have a low bias in this region.

Evaluating Sentinel-5P TROPOMI tropospheric NO2 column densities with airborne and Pandora spectrometers near New York City and Long Island Sound

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Interactive discussion

Peer-review completion

Post-review adjustments

Evaluating Sentinel-5P TROPOMI tropospheric NO₂ column densities with airborne and Pandora spectrometers near New York City and Long Island Sound