the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 26 May 2023
Measurement report: Ammonia in Paris derived from ground-based open-path and satellite observations
Abstract. Ammonia (NH3) is an important air pollutant which, as precursor of fine particulate matter, raises public health issues. This study analyzes 2.5-years of NH3 observations derived from ground-based (miniDOAS) and satellite (IASI) remote sensing instruments to quantify, for the first time, temporal variabilities (from interannual to diurnal) of NH3 concentrations in Paris.
The IASI and miniDOAS datasets are found to be in relatively good agreement (R > 0.70) when atmospheric NH3 concentrations are high and driven by regional agricultural activities. Over the investigated period (January 2020–June 2022), NH3 average concentrations in Paris measured by the miniDOAS and IASI are 2.23 μg.m−3 and 7.10 × 1015 molecules.cm−2, respectively, which are lower or equivalent to those documented in urban areas. The seasonal and monthly variabilities of NH3 concentrations in Paris are driven by sporadic agricultural emissions influenced by meteorological conditions, with NH3 concentrations in spring up to 2 times higher than in other seasons.
The potential source contribution function (PSCF) reveals that the close (100–200 km) east and northeast regions of Paris constitute the most important potential emission source areas of NH3 in the megacity.
Weekly cycles of NH3 derived from satellite and ground-based observations show different ammonia sources in Paris. In spring, agriculture has a major influence on ammonia concentrations and, in the other seasons, multi-platform observations suggest that ammonia is also controlled by traffic-related emissions.
In Paris, the diurnal cycle of NH3 concentrations is very similar to the one of NO2, with morning enhancements coincident with intensified road traffic. NH3 evening enhancements synchronous with rush hours are also monitored in winter and fall. NH3 concentrations measured during the weekends are consistently lower than NH3 concentrations measured during weekdays in summer and fall. This is a further evidence of a significant traffic source of NH3 in Paris.
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Notice on discussion status
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
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Preprint
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Supplement
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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1931 KB) - Metadata XML
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Supplement
(709 KB) - BibTeX
- EndNote
- Final revised paper
Journal article(s) based on this preprint
Interactive discussion
Status: closed
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RC1: 'Comment on egusphere-2023-963', Anonymous Referee #1, 11 Jul 2023
- AC1: 'Reply on RC1', Camille Viatte, 12 Sep 2023
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RC2: 'Comment on egusphere-2023-963', Anonymous Referee #2, 01 Aug 2023
Review of: Measurement report: Ammonia in Paris derived from ground-based open-path and satellite observations (Viatte et al., 2023)
The manuscript discusses relatively long-term NH3 measurements from the IASI instrument and a miniDOAS instrument located in the center of Paris. Correlation, seasonal and weekly cycles are discussed as well as the potential sources of the NH3 emissions. The manuscript is well-written and well structured. The findings do not introduce substantial new discoveries. The finding that traffic is a significant source of NH3 in the Paris region would be more convincing with a better placement of the miniDOAS or when NH3 measurements from more stations would have been included. Such measurements seem to be available in the Paris region. Although I find the study a bit lightweight for ACP, I still recommend its publication. However, revisions (detailed below) need to be conducted in the paper before publication. Please note that all questions/comments below should not only be addressed in the author’s reply, but also in the manuscript.
General comments
p.4 l. 103: One of the main comments is that a clear motivation is needed why you put the instrument at an altitude of 40 m above ground level. You are far less sensitive to the traffic related emissions you want to monitor as well? In the introduction (p.3 l.59) it is stated that this is badly monitored.
Fig.1 top panel: It is difficult to see the NH3 distribution in the Paris area on this map. It would be helpful to also provide a zoom for the red, blue and green box (maybe in appendix).
Fig.1 lower panel: I'm not sure if applying these different spatial criteria make much sense. Also it would be expected that when applying more strict spatial constraints (30 km) that the agreement would be better, due to better co-location, which is not the case. Please explain.
Fig.1 lower panel: Moreover, why don't you make use of the maximum spatial resolution of IASI, i.e. comparing with the closest pixel or smaller radius especially as you mention city-scale studies earlier on.
Fig.1 lower panel: Please explain the spread of data points over the seasons. Why do you have significantly more points in spring than in summer and other seasons?
p.7 l.173: The satellite retrievals are strongly impacted by thermal contrast. It is highly surprising and difficult to believe that there is no impact of temperature on the correlation as it affects the sensitivity of the satellite data. On the other hand near-surface measurements are highly impacted by PBL height, while this is less the case for the column observations. Please explain.
p.7 l.177: If I understand it correctly, in the further analysis you average the IASI retrievals within a box of 50 km e.g. to compare with miniDOAS? In that case you cannot speak about a city-scale study neither about studying the spatiotemporal variability in Paris. Temporal yes, but not spatial!
p.7 l.186: Please describe here or provide a reference how the error budget is done.
p.8 l.199: Agreed, but vertically you are also at large distance from the potential traffic emission source that you want to assess in this study, when not putting it at the surface. Official monitoring stations usually sample at 3 m altitude. This might also explain why you measure lower concentrations than in other urban areas / other studies.
p.15 l. 376: If the data from this traffic station (and maybe others) is available, why isn’t it used in this study, even if it isn’t a miniDOAS? It would make your results far more convincing, e.g. to check if the results are consistent for different stations and to assess the effect of having the miniDOAS at 40 m.
Minor comments
p.4 l.88: Would be good to include as well https://amt.copernicus.org/articles/9/2721/2016/amt-9-2721-2016.pdf
p.8 l.202: I assume you provide first averages and after min max ranges? Please specify the numbers that are provided here.
p.8 l.212: Please elaborate shortly on these high pollution events.
p.10 L.250: It is not really clear why this is then only the case in 2021, and for example not seen in 2020?
p.12 l.296: Please elaborate on why this is observed in agricultural areas. Is it related to reduced agricultural activity over the weekend?
Technical corrections
p.1 l.20: in other urban areas
p.3 l.62: replace ‘monitored’ by ‘detected’?
p.7 l.156: do you mean quantitatively?
p.11 l.278: ‘raw’ should be ‘row’
p.15 l.380: I suggest replacing ‘Atmospheric’ by ’Temporal’
Citation: https://doi.org/10.5194/egusphere-2023-963-RC2 - AC2: 'Reply on RC2', Camille Viatte, 12 Sep 2023
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2023-963', Anonymous Referee #1, 11 Jul 2023
- AC1: 'Reply on RC1', Camille Viatte, 12 Sep 2023
-
RC2: 'Comment on egusphere-2023-963', Anonymous Referee #2, 01 Aug 2023
Review of: Measurement report: Ammonia in Paris derived from ground-based open-path and satellite observations (Viatte et al., 2023)
The manuscript discusses relatively long-term NH3 measurements from the IASI instrument and a miniDOAS instrument located in the center of Paris. Correlation, seasonal and weekly cycles are discussed as well as the potential sources of the NH3 emissions. The manuscript is well-written and well structured. The findings do not introduce substantial new discoveries. The finding that traffic is a significant source of NH3 in the Paris region would be more convincing with a better placement of the miniDOAS or when NH3 measurements from more stations would have been included. Such measurements seem to be available in the Paris region. Although I find the study a bit lightweight for ACP, I still recommend its publication. However, revisions (detailed below) need to be conducted in the paper before publication. Please note that all questions/comments below should not only be addressed in the author’s reply, but also in the manuscript.
General comments
p.4 l. 103: One of the main comments is that a clear motivation is needed why you put the instrument at an altitude of 40 m above ground level. You are far less sensitive to the traffic related emissions you want to monitor as well? In the introduction (p.3 l.59) it is stated that this is badly monitored.
Fig.1 top panel: It is difficult to see the NH3 distribution in the Paris area on this map. It would be helpful to also provide a zoom for the red, blue and green box (maybe in appendix).
Fig.1 lower panel: I'm not sure if applying these different spatial criteria make much sense. Also it would be expected that when applying more strict spatial constraints (30 km) that the agreement would be better, due to better co-location, which is not the case. Please explain.
Fig.1 lower panel: Moreover, why don't you make use of the maximum spatial resolution of IASI, i.e. comparing with the closest pixel or smaller radius especially as you mention city-scale studies earlier on.
Fig.1 lower panel: Please explain the spread of data points over the seasons. Why do you have significantly more points in spring than in summer and other seasons?
p.7 l.173: The satellite retrievals are strongly impacted by thermal contrast. It is highly surprising and difficult to believe that there is no impact of temperature on the correlation as it affects the sensitivity of the satellite data. On the other hand near-surface measurements are highly impacted by PBL height, while this is less the case for the column observations. Please explain.
p.7 l.177: If I understand it correctly, in the further analysis you average the IASI retrievals within a box of 50 km e.g. to compare with miniDOAS? In that case you cannot speak about a city-scale study neither about studying the spatiotemporal variability in Paris. Temporal yes, but not spatial!
p.7 l.186: Please describe here or provide a reference how the error budget is done.
p.8 l.199: Agreed, but vertically you are also at large distance from the potential traffic emission source that you want to assess in this study, when not putting it at the surface. Official monitoring stations usually sample at 3 m altitude. This might also explain why you measure lower concentrations than in other urban areas / other studies.
p.15 l. 376: If the data from this traffic station (and maybe others) is available, why isn’t it used in this study, even if it isn’t a miniDOAS? It would make your results far more convincing, e.g. to check if the results are consistent for different stations and to assess the effect of having the miniDOAS at 40 m.
Minor comments
p.4 l.88: Would be good to include as well https://amt.copernicus.org/articles/9/2721/2016/amt-9-2721-2016.pdf
p.8 l.202: I assume you provide first averages and after min max ranges? Please specify the numbers that are provided here.
p.8 l.212: Please elaborate shortly on these high pollution events.
p.10 L.250: It is not really clear why this is then only the case in 2021, and for example not seen in 2020?
p.12 l.296: Please elaborate on why this is observed in agricultural areas. Is it related to reduced agricultural activity over the weekend?
Technical corrections
p.1 l.20: in other urban areas
p.3 l.62: replace ‘monitored’ by ‘detected’?
p.7 l.156: do you mean quantitatively?
p.11 l.278: ‘raw’ should be ‘row’
p.15 l.380: I suggest replacing ‘Atmospheric’ by ’Temporal’
Citation: https://doi.org/10.5194/egusphere-2023-963-RC2 - AC2: 'Reply on RC2', Camille Viatte, 12 Sep 2023
Peer review completion
Journal article(s) based on this preprint
Data sets
IASI BC data AM Viatte Camille https://zenodo.org/record/7962362
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Camille Viatte
Nadir Guendouz
Clarisse Dufaux
Arjan Hensen
Daan Swart
Martin Van Damme
Lieven Clarisse
Pierre Coheur
Cathy Clerbaux
The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(1931 KB) - Metadata XML
-
Supplement
(709 KB) - BibTeX
- EndNote
- Final revised paper