Comparison of tropospheric NO<sub>2</sub> columns from MAX-DOAS retrievals and regional air quality model simulations

Blechschmidt, Anne-Marlene; Arteta, Joaquim; Coman, Adriana; Curier, Lyana; Eskes, Henk; Foret, Gilles; Gielen, Clio; Hendrick, Francois; Marécal, Virginie; Meleux, Frédérik; Parmentier, Jonathan; Peters, Enno; Pinardi, Gaia; Piters, Ankie J. M.; Plu, Matthieu; Richter, Andreas; Segers, Arjo; Sofiev, Mikhail; Valdebenito, Álvaro M.; Van Roozendael, Michel; Vira, Julius; Vlemmix, Tim; Burrows, John P.

doi:https://doi.org/10.5194/acp-20-2795-2020

Articles | Volume 20, issue 5

https://doi.org/10.5194/acp-20-2795-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 3.0 License.

https://doi.org/10.5194/acp-20-2795-2020

© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 3.0 License.

Articles | Volume 20, issue 5

Research article

|

06 Mar 2020

Research article |

| 06 Mar 2020

Comparison of tropospheric NO₂ columns from MAX-DOAS retrievals and regional air quality model simulations

Anne-Marlene Blechschmidt, Joaquim Arteta, Adriana Coman, Lyana Curier, Henk Eskes, Gilles Foret, Clio Gielen, Francois Hendrick, Virginie Marécal, Frédérik Meleux, Jonathan Parmentier, Enno Peters, Gaia Pinardi, Ankie J. M. Piters, Matthieu Plu, Andreas Richter, Arjo Segers, Mikhail Sofiev, Álvaro M. Valdebenito, Michel Van Roozendael, Julius Vira, Tim Vlemmix, and John P. Burrows

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Final revised paper (published on 06 Mar 2020)
Preprint (discussion started on 01 Mar 2017)

Interactive discussion

Status: closed

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

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RC1: 'Referee #3: review', Anonymous Referee #3, 16 Mar 2017
- AC1: 'Response to anonymous referee #3', A. -M. Blechschmidt, 06 Sep 2018
RC2: 'referee comment', Anonymous Referee #1, 24 Mar 2017
- AC2: 'Response to anonymous referee #1', A. -M. Blechschmidt, 06 Sep 2018
RC3: 'Referee Comment', Anonymous Referee #2, 28 Mar 2017
- AC3: 'Response to anonymous referee #2', A. -M. Blechschmidt, 06 Sep 2018

Peer-review completion

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

AR by A. -M. Blechschmidt on behalf of the Authors (06 Sep 2018) Author's response Manuscript

ED: Referee Nomination & Report Request started (10 Sep 2018) by Tim Butler

RR by Anonymous Referee #1 (14 Sep 2018)

RR by Anonymous Referee #2 (02 Oct 2018)

Suggestions for revision or reasons for rejection

Despite addressing several of the previous comments and representing a worthwhile effort. if further improved, the revised manuscript fails to address my larger concerns. The language of the writing is informal, the comparisons in the text are qualitative in nature, and the conclusions of the study are too general. In its current form, the manuscript presents a lot of data and a lot of model results, and then lists many factors that could affect both model and observation, but does not provide a satisfying conclusion or an articulate path forward on how future studies might reach conclusions. The first two paragraphs of the Summary and Conclusions section highlight the concerns discussed above:

“The reasons for differences between model results and observations found by the comparisons are discussed here in a general sense and need to be further investigated by carrying out additional dedicated model runs in future modelling studies. In general, differences between simulated and retrieved tropospheric NO2 VCDs as well as surface partial columns found in this study could result from model uncertainties in chemistry and meteorology or a combination of both. Moreover, errors related to NOx emission inventories or uncertainties in tropospheric MAX-DOAS retrievals may also contribute to differences between simulated and retrieved values found in this study.

“Our analysis shows that in general and on average the model ensemble does well represent tropospheric NO2 amounts observed by MAX-DOAS. However, many points to evaluate arise from the MAX-DOAS based comparisons. Tracking down the reasons for differences between simulations and retrievals and adjusting model runs accordingly (in case of differences caused by errors in simulations rather than uncertainties of the retrievals) could improve model performance substantially.”

The paper would be improved considerably if the documentation of results was more cohesively and coherently described, removing speculative statements on the cause of discrepancies between models and observations, which only distract from the worthwhile effort to document the discrepancies common to models, between the models and how we could use this information to inform future studies. Currently, the authors prescribe future studies to answer a variety of pressing questions without providing much direction on how the dataset can be used to do so.

It is not clear why the authors present new analysis and discussion of model resolution effects in the middle of the summary and conclusions section – P19 L22 – P20 L3

Specific comments:

P2 L8-22 – Much of this content is general atmospheric chemistry knowledge and does not have much relevance for the rest of the material (e.g., PAN is not mentioned once after this section)

P3 L26 "In contrast to NO2, NOx cannot be retrieved from MAX-DOAS ... so that these measurements of more interest for air quality than atmospheric chemistry studies." I do not understand why NO2 is of more interest to air quality than atmospheric chemistry studies as stated in the manuscript.

P4 31-33 – Consider editing or deleting for clarity

P5 21 – “More details on specific model setups and scores with respect to surface observations” – Consider editing.

P8 L17-20 – The data screening metrics described here are qualitative. Add quantitative detail.

P9 - The inclusion of several paragraphs and two equations describing weighted and unweighted average of a quantity is not necessary.

P14 L32-35 – This information belongs in the caption of a figure, not in the main body of the text.

P15 L7 – “There is an overestimation of wintertime values while summertime values are better reproduced by the model ensemble. This may indicate that the model ensemble overestimates production of OH via photolysis of O3 when less light is available, as OH acts as a sink for NO2” The reasoning demonstrated here is representative of reasoning throughout the document – a single process is singled out as the potential source of discrepancy seemingly at random from a multitude of potential causes. I recommend that the authors refrain from speculating on sources of difference without more exhaustive and conclusive analysis. It distracts from the worthwhile pursuit of a thorough documenting of the differences.

P20 L4-6 “A pollution plume and related increase in the time series of tropospheric NO2 VCDs observed by MAX-DOAS would be expected to be reproduced better by model runs with higher horizontal resolution compared to lower resolution runs. The lifetime of NO2 is also expected to increase with model resolution.” Please use terms like finer and coarser to describe resolution as lower and higher can be confusing.

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ED: Reconsider after major revisions (04 Oct 2018) by Tim Butler

AR by A. -M. Blechschmidt on behalf of the Authors (29 Nov 2019) Author's response Manuscript

ED: Publish as is (16 Jan 2020) by Tim Butler

AR by A. -M. Blechschmidt on behalf of the Authors (20 Jan 2020)

Short summary

MAX-DOAS tropospheric NO₂ vertical column retrievals from a set of European measurement stations are compared to regional air quality models which contribute to the operational Copernicus Atmosphere Monitoring Service (CAMS). Correlations are on the order of 35 %–75 %; large differences occur for individual pollution plumes. The results demonstrate that future model development needs to concentrate on improving representation of diurnal cycles and associated temporal scalings.

Comparison of tropospheric NO2 columns from MAX-DOAS retrievals and regional air quality model simulations

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Comparison of tropospheric NO₂ columns from MAX-DOAS retrievals and regional air quality model simulations