the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 30 Apr 2024
Analysis of ozone vertical profile day-to-day variability in the lower troposphere during the Paris-2022 ACROSS campaign
Abstract. The ozone vertical profiles variability in the lower troposphere is analyzed during the summer 2022 ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) measurement campaign as part of the PANAME (PAris region urbaN Atmospheric observations and models for Multidisciplinary rEsearch) project. The analysis is based on 21 days of DIfferential Absorption Lidar (DIAL) observations, in addition to the two daily vertical ozone profiles measured by In-service Aircraft for a Global Observing System (IAGOS) flights to and from Paris airport. The ACROSS ozone profiles are also a good opportunity to assess the lowermost tropospheric ozone column retrieval by the satellite observations of Infrared Atmospheric Sounding Interferometer (IASI). The planetary boundary layer (PBL) vertical structure evolution is monitored using a 808-nm microlidar and meteorological radiosondes launched in the city center. Characterization of the regional transport of polluted air masses advected over the city is based on the daily ozone analysis of the Copernicus Atmospheric Service (CAMS) ensemble model and on backward trajectories of the Paris city plume. This work show that the CAMS simulations of the Paris ozone plume between the surface and 3 km are consistent with the ACROSS ozone vertical profiles and that the IASI satellite observations can capture the day to day variability of the 0–3 km lowermost ozone column if the contribution of the surface column below 1.2 km is lower than 4 DU. The day time ozone vertical structure above the city center is also in good agreement with the PBL growth during the day and with the formation of the residual layer during the night. The O3 DIAL may provide additional information about the PBL vertical structure to discuss differences between microlidar and radiosounding measurements of the PBL height.
In addition to the well-known control of the ozone photochemical production by atmospheric temperature, cloud cover and mixing between the surface layer (0–500 m) and the residual layer, the comparison of four ozone pollution events shows that the thickness of the PBL during the day and the advection of regional scale plumes above the PBL can significantly change the ozone concentrations above Paris city center. With similar cloud cover and air temperature, high ozone concentrations up to 180 µg.m-3 are encountered during the day when PBL height is below 1.5 km, while they remain below 150 µg.m-3 when PBL height increases above 2.5 km. Advection of ozone poor concentrations in the free troposphere during a Saharan dust event is able to mitigate the ozone photochemical production. On the other hand, the advection of a continental pollution plume with high ozone concentrations > 140 µg.m-3 maintained high concentrations in the surface layer despite a temperature decrease and cloud cover development.
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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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The requested preprint has a corresponding peer-reviewed final revised paper. You are encouraged to refer to the final revised version.
- Preprint
(11617 KB) - Metadata XML
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Supplement
(1421 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-2024-892', Anonymous Referee #1, 21 May 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-892/egusphere-2024-892-RC1-supplement.pdf
- AC1: 'Reply on RC1', Gerard Ancellet, 22 Aug 2024
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RC2: 'Comment on egusphere-2024-892', Anonymous Referee #2, 28 May 2024
Summary: DIAL Ozone profiles and IAGOS in situ data are presented during the 2022 ACROSS campaign on 21 days. These profiles are compared to the the satellite observations of Infrared Atmospheric Sounding Interferometer (IASI). Ancillary measurements from microlidar and radiosondes are also used for contextualizing the dynamics of the atmosphere. To better understand the regional transport of polluted air masses advected over the city, daily ozone analysis of the Copernicus Atmospheric Service (CAMS) ensemble model 10 and on backward trajectories of the Paris city plume were also utilized.
Major Comments: This paper aims to discuss the importance of DIAL profiles on understanding the pollution transport on several high ozone days during ACROSS 2022. This effort is unfortunately not very well documented or referenced and reads closer to a campaign report, rather than a scientifically significant manuscript. There is mention of pollution and ozone precursors, but the authors have failed to pull in any sort of additional chemical observations besides ozone. CAMS or IAGOS NOx or other species will help bolster the conclusions of pollution transport or why there are potentially differences between the measurements. Furthermore, the IASI measurements are not carefully assessed, some work needs to be done in understanding the inherent value and uncertainty of these measurements. Comments below are intended to help the paper form a more thorough conclusion.
Minor Comments: There is a lack of appropriate and topical references throughout most of the manuscript. References to previous air quality/ozone campaigns should be refreshed for more recent work, in addition to expanding to other megacities.
L90 – Reference needed as to where this statement can be drawn from “The accuracy of the lidar observations is altitude-dependent being of the order of 7µg.m−3 below 1000 m and occasionally increases up to 20 µg.m−3 above 2 km at midday”. Also recommend adding in a percentage difference. Please also note somewhere the conversion to ppbv for these observations - 1 ppb O3 = 1.96 µg/m3 at 25°C and 1 atm
Fig. 3 – Higher resolution terrain maps in the background would help better understand the ozone transport throughout the time. Adding in the wind barbs would also contextualize which direction the plume was moving.
Fig 6b – Is the CBLH actually over 3.5-3.8km? This seems unrealistic, even with >30C temperatures. Is this an aged polluted air mass that has recirculated associated with the synoptic high pressure system over the area as mentioned in the text. This figure should be clarified or manual inspection of the the CLBH algorithm should be addressed. How did CAMS compare in terms of the RL and CLBH observations?
Fig 9 – It’s unclear where and when these IAGOS data overlap. For instance on 20220615, what is the coindidence in time for the CAMS (or IAGOS) and DIAL?
Table 2 – are the +/- associated with the variance of the dataset or uncertainty associated with the observations? The relative levels of uncertainty between high precision DIAL and in-situ observations needs to be described in comparison to the likely much higher uncertainty satellite observations.
L305 – This statement regarding excellent agreement cannot be fully stated until the uncertainty estimations are presented or some level of description of the apriori data for IASI is described. References are critically needed throughout this section.
Figure 13 – The IAGOS data does not replicate some of the higher ozone concentrations as observed in the DIAL measurements. What is the reason for this? This should also be labeled Partial Ozone columns in the x-axis.
Section 5.2 - This could be better visualized by bringing at least one of the FLEXPART simulation plots to the main paper rather than the supplemental.
Citation: https://doi.org/10.5194/egusphere-2024-892-RC2 - AC2: 'Reply on RC2', Gerard Ancellet, 22 Aug 2024
Interactive discussion
Status: closed
-
RC1: 'Comment on egusphere-2024-892', Anonymous Referee #1, 21 May 2024
The comment was uploaded in the form of a supplement: https://egusphere.copernicus.org/preprints/2024/egusphere-2024-892/egusphere-2024-892-RC1-supplement.pdf
- AC1: 'Reply on RC1', Gerard Ancellet, 22 Aug 2024
-
RC2: 'Comment on egusphere-2024-892', Anonymous Referee #2, 28 May 2024
Summary: DIAL Ozone profiles and IAGOS in situ data are presented during the 2022 ACROSS campaign on 21 days. These profiles are compared to the the satellite observations of Infrared Atmospheric Sounding Interferometer (IASI). Ancillary measurements from microlidar and radiosondes are also used for contextualizing the dynamics of the atmosphere. To better understand the regional transport of polluted air masses advected over the city, daily ozone analysis of the Copernicus Atmospheric Service (CAMS) ensemble model 10 and on backward trajectories of the Paris city plume were also utilized.
Major Comments: This paper aims to discuss the importance of DIAL profiles on understanding the pollution transport on several high ozone days during ACROSS 2022. This effort is unfortunately not very well documented or referenced and reads closer to a campaign report, rather than a scientifically significant manuscript. There is mention of pollution and ozone precursors, but the authors have failed to pull in any sort of additional chemical observations besides ozone. CAMS or IAGOS NOx or other species will help bolster the conclusions of pollution transport or why there are potentially differences between the measurements. Furthermore, the IASI measurements are not carefully assessed, some work needs to be done in understanding the inherent value and uncertainty of these measurements. Comments below are intended to help the paper form a more thorough conclusion.
Minor Comments: There is a lack of appropriate and topical references throughout most of the manuscript. References to previous air quality/ozone campaigns should be refreshed for more recent work, in addition to expanding to other megacities.
L90 – Reference needed as to where this statement can be drawn from “The accuracy of the lidar observations is altitude-dependent being of the order of 7µg.m−3 below 1000 m and occasionally increases up to 20 µg.m−3 above 2 km at midday”. Also recommend adding in a percentage difference. Please also note somewhere the conversion to ppbv for these observations - 1 ppb O3 = 1.96 µg/m3 at 25°C and 1 atm
Fig. 3 – Higher resolution terrain maps in the background would help better understand the ozone transport throughout the time. Adding in the wind barbs would also contextualize which direction the plume was moving.
Fig 6b – Is the CBLH actually over 3.5-3.8km? This seems unrealistic, even with >30C temperatures. Is this an aged polluted air mass that has recirculated associated with the synoptic high pressure system over the area as mentioned in the text. This figure should be clarified or manual inspection of the the CLBH algorithm should be addressed. How did CAMS compare in terms of the RL and CLBH observations?
Fig 9 – It’s unclear where and when these IAGOS data overlap. For instance on 20220615, what is the coindidence in time for the CAMS (or IAGOS) and DIAL?
Table 2 – are the +/- associated with the variance of the dataset or uncertainty associated with the observations? The relative levels of uncertainty between high precision DIAL and in-situ observations needs to be described in comparison to the likely much higher uncertainty satellite observations.
L305 – This statement regarding excellent agreement cannot be fully stated until the uncertainty estimations are presented or some level of description of the apriori data for IASI is described. References are critically needed throughout this section.
Figure 13 – The IAGOS data does not replicate some of the higher ozone concentrations as observed in the DIAL measurements. What is the reason for this? This should also be labeled Partial Ozone columns in the x-axis.
Section 5.2 - This could be better visualized by bringing at least one of the FLEXPART simulation plots to the main paper rather than the supplemental.
Citation: https://doi.org/10.5194/egusphere-2024-892-RC2 - AC2: 'Reply on RC2', Gerard Ancellet, 22 Aug 2024
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Gerard Ancellet
Camille Viatte
Anne Boynard
François Ravetta
Jacques Pelon
Cristelle Cailteau-Fischbach
Pascal Genau
Julie Capo
Axel Roy
Philippe Nédélec
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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