Session AS5.9

[Programme]

AS5.9 | Urban to rural atmospheric observations and models for multidisciplinary research

Urban to rural atmospheric observations and models for multidisciplinary research

Convener: Christopher Cantrell | Co-conveners: Eleonora Aruffo, John N. Crowley, Chiara Giorio, Valérie Gros

Orals

| Wed, 26 Apr, 16:15–18:00 (CEST)

Room M2

Posters on site

| Attendance Wed, 26 Apr, 14:00–15:45 (CEST)

Hall X5

Understanding the physical and chemical processes that take place in the atmosphere benefits from observations of its dynamics and composition in a variety of conditions and situations. To accomplish this, scientists employ instrumentation for in situ and remotely sensed quantities from a variety of ground, airborne, and space-based platforms. In 2022, several observational field campaigns related to tropospheric composition and dynamics in urban and suburban environments were conducted throughout the globe, and especially during the summer in Paris under the framework of the PANAME (PAris region urbaN Atmospheric observations and models for Multidisciplinary rEsearch) 2022 initiative. While these projects had a variety of specific goals, some of them were designed to examine aspects of the evolution of urban and rural air masses as they are transported from cities to the surrounding peri-urban, suburban, and rural areas. Such studies complement investigations of strictly urban or rural environments including air quality and its link with urban or suburban vegetation, urban meteorology, cities and climate change, and climate in cities and the link with human activities and health. Some of these projects also specifically examine aspects of the evolution of urban air masses as they are transported from cities to the surrounding peri urban, suburban, and rural areas.

Presentations in this session will describe measurements performed during the 2022 campaigns in Paris region and other megacities measurements of quantities observed during the 2022 campaign season, while providing initial and first analyses of the observations including employing numerical models. The primary goal of the session is to identify findings related to new or poorly understood chemical and physical processes associated with emission, transport, and transformation of substances in megacities and within the framework of transitions from urban-to-rural environments, as well as new insights into urban-suburban meteorology and dynamics.

Orals: Wed, 26 Apr | Room M2

Chairpersons: Chiara Giorio, Vincent Michoud

16:15–16:20

5-minute convener introduction

16:20–16:30

EGU23-17485

AS5.9

Highlight

On-site presentation

Meteorological variability and regional pollutant distributions during the summer 2022 ACROSS/PANAME campaign

Matthias Beekmann, Guillaume Siour, Ludovico Di Antonio, Gilles Foret, Frederic Meleux, Augustin Colette, Amandine Rosso, Claudia Di Biagio, Juan Cuesta, Paola Formenti, Aline Gratien, Martial Haeffelin, Simone Kotthaus, Valery Masson, Vincent Michoud, and Christopher Cantrell

The international ACROSS (Atmospheric ChemistRy Of the Suburban forest) intensive field measurement campaign (supported by the Make Our Planet Great Again initiative) took place from June 13 to July 25 2022 in and around the Ile-de-France during an exceptional hot (more than 3°C above the climatological mean for France) and dry summer season. This work will provide a broad classification of weather conditions that occurred during the campaign, useful for further analysis of observations and simulations. Weather scenarios will be analysed in terms of synoptic weather situations, relating transport patterns (regional advection to the Ile-de-France region, plumes from Paris agglomeration), temperature and relative humidity evolution. During the June-July 2022 period, several distinct weather and pollution patterns occurred, among which: (1) two strong heatwaves, with large photochemical activity promoting secondary pollutants build-up (O₃, SOA), (2) advection of relatively clean oceanic air masses, and (3) Saharan dust and intense forest fire events with dust and fire aerosol advection to the Ile-de-France region. The analysis is based on meteorological data from several models (GFS, WRF, ARPEGE, AROME) and observations, pollution forecasts from the French Prev’Air system (http://www2.prevair.org/), and from the AirParif Esmeralda platform (http://www.esmeralda-web.fr/accueil/) that have been used for the airborne campaign support. In addition, dedicated simulations with the CHIMERE model (see companion abstract by Di Antonio et al. for this session), and major pollutant observations by air quality networks, from satellites, or performed within ACROSS will be used to analyse how meteorological conditions and weather patterns impacted the spatial distributions of major primary and secondary chemical species. Especially tracers of anthropogenic and biogenic emissions and photochemical activity (O₃, PM_2.5, OA, BC, NOx, BVOC) will be analysed.

Keywords: Meteorology, pollutant distributions, transport patterns, ACROSS, MOPGA

How to cite: Beekmann, M., Siour, G., Di Antonio, L., Foret, G., Meleux, F., Colette, A., Rosso, A., Di Biagio, C., Cuesta, J., Formenti, P., Gratien, A., Haeffelin, M., Kotthaus, S., Masson, V., Michoud, V., and Cantrell, C.: Meteorological variability and regional pollutant distributions during the summer 2022 ACROSS/PANAME campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17485, https://doi.org/10.5194/egusphere-egu23-17485, 2023.

16:30–16:40

EGU23-11896

AS5.9

ECS

Virtual presentation

Atmospheric Chemistry linked to HOx radicals of a Suburban Forest during the ACROSS summer Field Campaign

Nesrine Shamas, Sebastien Batut, Amaury Lahccen, Vincent Michoud, Christopher Cantrell, Sébastien Dusanter, Joel Brito, Alexandre Tomas, Ahmad Lahib, Marina Jamar, Christa Fittschen, and Coralie Schoemaecker

Atmospheric Chemistry linked to HO_x radicals of a Suburban Forest during the ACROSS summer Field Campaign

Nesrine. Shamas¹, Sebastien. Batut¹, Amaury. Lahccen¹, Vincent Michoud², Christopher Cantrell³, Sébastien Dusanter⁴, Joel Brito⁴, Alexandre Tomas⁴, Ahmad Lahib⁴, Marina Jamar⁴, Christa. Fittschen¹, Coralie. Schoemaecker¹

¹ PC2A, CNRS – University Lille, Bât. C11, Cité Scientifique, Villeneuve d’Ascq, France

² LISA, CNRS – Université Paris Cité and Université Paris-Est Créteil, F-94010 Créteil, France

³ LISA, CNRS – Université Paris-Est Créteil and Université Paris Cité, F-94010 Créteil, France

⁴1IMT Nord Europe, Institut Mines-Télécom, Univ. Lille, Center for Energy and Environment, F-59000 Lille, France

Paris, one of the largest European megacities, transports pollution to different surrounding areas depending on the variation of the wind direction associated with specific meteorological conditions. The relatively unique situation of this isolated megacity from other urban areas make it a suitable location to study the impact of urban emissions on the chemistry of close biogenic environments such as forests and vice versa. In order to investigate this influence, the ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) field campaign was performed during summer 2022, with a measurement site located in the Rambouillet forest. The combination of the data provided during this field campaign from different research groups (such as measurements of VOCs, inorganic species, particle concentration and composition, …) will allow a better understanding of the influence of mixing anthropogenic urban or oceanic air masses, leading to different NO concentrations, with biogenic forestry emissions on the oxidation of tropospheric VOCs. This will ultimately help improving this chemistry within atmospheric models. The UL-FAGE instrument was deployed during the ACROSS campaign, where different types of measurements were performed: OH, HO₂, RO_xradical quantification at the ground level and OH reactivity. The OH reactivity was alternatively measured at two different levels: below (ground level) and above the forest canopy (top of a 40 m tower). Clear stratification was observed during the night with a higher OH reactivity at the ground level than above the canopy. Comparison between the measured and the calculated OH reactivity allows to identify the diurnal missing reactivity at both levels. Preliminary results of the OH reactivity and the radical quantification will be presented.

References

[1] Baklanov et al., Advances in Science and Research, 4, 115–120, 2010

[2] MEGAPOLI campaign 2009-2010 special issue, https://acp.copernicus.org/articles/special_issue248.html page, accessed 24 May 2019

How to cite: Shamas, N., Batut, S., Lahccen, A., Michoud, V., Cantrell, C., Dusanter, S., Brito, J., Tomas, A., Lahib, A., Jamar, M., Fittschen, C., and Schoemaecker, C.: Atmospheric Chemistry linked to HOx radicals of a Suburban Forest during the ACROSS summer Field Campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11896, https://doi.org/10.5194/egusphere-egu23-11896, 2023.

16:40–16:50

EGU23-17265

AS5.9

Highlight

On-site presentation

Observations of trace gases above & below a forest canopy during ACROSS

Sébastien Dusanter, Joel de Brito, Ahmad Lahib, Alexandre Tomas, Marina Jamar, Estephanie Alhajj Moussa, Astrid Bauville, Christopher Cantrell, Vincent Michoud, Mathieu Cazaunau, Paola Formenti, Fanny Bachelier, Benoit Grosselin, Max McGillen, Veronique Daele, Wahid Mellouki, Chaoyang Xue, Jérôme Houny, and Alexandre Kukui

The ACROSS campaign (Atmospheric chemistry of the suburban forest) is a collaborative effort to better understand how the mixing between urban and biogenic air masses impacts atmospheric composition and reactivity. A main objective is to provide a detailed description of physico-chemical processes involved in atmospheric transformations of biogenic Volatile Organic Compounds (VOCs), and the myriad of intermediate species formed as a consequence, which have yet to be characterized. This multi-platform campaign took place during summer 2022 for a duration of 6 weeks and included a supersite in the Rambouillet forest located on the path of pollution plumes from Paris. An unprecedented suite of analytical instruments was deployed at this site to probe air masses at the ground level and above the forest canopy using a 40-m tower.
This presentation will focus on trace gas observations, including VOCs, RO_x (OH+HO₂+RO₂) and selected inorganic species (O₃, NO_x – NO+NO₂), both above and below the forest canopy. A descriptive analysis will be presented to highlight biogenic VOC oxidation regimes taking place under unpolluted (oceanic air masses) and polluted (Paris plumes) conditions, with a focus on primary/secondary species. Chemical compositions observed above and below-canopy will also be contrasted. On the basis of these observations, this presentation will highlight scientific questions related to RO_x, VOC and NO_x budgets that will be further investigated to fill important gaps in our understanding of biogenic VOC transformations and secondary organic aerosol formation.

Acknowledgments. This work is supported by the French national research agency (ANR-20-CE01-0010) & LABEX-CaPPA (ANR-11-LABX-005-01) and the French national program LEFE/CHAT INSU.

How to cite: Dusanter, S., de Brito, J., Lahib, A., Tomas, A., Jamar, M., Alhajj Moussa, E., Bauville, A., Cantrell, C., Michoud, V., Cazaunau, M., Formenti, P., Bachelier, F., Grosselin, B., McGillen, M., Daele, V., Mellouki, W., Xue, C., Houny, J., and Kukui, A.: Observations of trace gases above & below a forest canopy during ACROSS, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17265, https://doi.org/10.5194/egusphere-egu23-17265, 2023.

16:50–17:00

EGU23-309

AS5.9

ECS

On-site presentation

Measurement of Highly Oxygenated Organic Compounds at the Rambouillet forest during the ACROSS Campaign

Estephanie Alhajj Moussa, Vincent Michoud, Paola Formenti, Manuela Cirtog, Bénédicte Picquet-Varrault, Sergio Harb, Mathieu Cazaunau, Aline Gratien, Claudia Di Biagio, Emmanuel Tison, Joel F. de Brito, Sebastien Dusanter, Veronique Riffault, Nadine Locoge, Ahmad Lahib, Alexandre Tomas, Marina Jamar, Pablo Espina-Martin, and Christopher Cantrell

Global population increase has placed pressure on available resources and has resulted in the emission of a variety of trace gases into the troposphere that includes volatile organic compounds (VOCs). This class of molecules plays major roles in the formation of secondary products such as secondary organic aerosol (SOA) and tropospheric ozone, which adversely affect Earth’s climate and human health. Research has continued to reveal more details of complex atmospheric degradation processes involving VOCs of both anthropogenic and biogenic origins, but relatively few have been directly studied including the possible impacts of mixing of air masses of anthropogenic and biogenic origins. The ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) project aims to improve our knowledge of atmospheric chemical processes that occur in such mixed air masses and their impact on air quality. The experimental strategy of ACROSS is based on ground-based and airborne observations during an international, large-scale, comprehensive, multi-platform, multi-site field campaign that took place in the summer of 2022 in the greater Paris and suburban forested areas.

As VOCs are processed in the atmosphere, secondary compounds are produced including highly oxygenated organic molecules (HOMs) that are a subset of low volatility organic compounds characterized by their contribution to formation and ageing of SOA. Nitrate ion chemical ionization (CI), coupled with an Atmospheric Pressure Interface−Time-Of-Flight Mass Spectrometer (API-TOF-MS) is an online analytical technique that detects and quantifies gas-phase HOMs (and other compounds) with high sensitivity and mass resolution in the atmosphere or laboratory systems. This instrument provides measurements that help to fill the observational gap between the aerosol and gas phases.

The instrument was deployed at the top of a 40 m tower (above the canopy) in the Rambouillet forest site during the ACROSS field campaign to measure and identify HOMs formed mainly under two different composition regimes: biogenic emissions only, and biogenic air/urban air mixtures. The data collected by the instrument will be presented and used to enhance understanding of the chemical formation pathways of HOMs and their contribution to the composition of aerosols.

How to cite: Alhajj Moussa, E., Michoud, V., Formenti, P., Cirtog, M., Picquet-Varrault, B., Harb, S., Cazaunau, M., Gratien, A., Di Biagio, C., Tison, E., F. de Brito, J., Dusanter, S., Riffault, V., Locoge, N., Lahib, A., Tomas, A., Jamar, M., Espina-Martin, P., and Cantrell, C.: Measurement of Highly Oxygenated Organic Compounds at the Rambouillet forest during the ACROSS Campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-309, https://doi.org/10.5194/egusphere-egu23-309, 2023.

17:00–17:10

EGU23-437

AS5.9

ECS

Highlight

On-site presentation

Nighttime concentrations of NO3 and N2O5 in mixed anthropogenic/biogenic air masses during the ACROSS campaign

Sergio Harb, Manuela Cirtog, Mathieu Cazaunau, Maxime Feingesicht, Vincent Michoud, Xavier Landsheere, Edouard Pangui, Estephanie Alhajj Moussa, Antonin Berge, Christopher Cantrell, and Benedicte Picquet-Varrault

The nitrate radical (NO₃) is mainly formed in the atmosphere through the reaction of nitrogen dioxide (NO₂) with ozone (O₃). It accumulates at night because during the day its photolysis in sunlight and its rapid reaction with nitric oxide (NO) can rapidly consume it. NO₃ radical is a major nighttime atmospheric oxidant of biogenic volatile organic compounds (BVOCs), which represent alone 75 to 90% of global non-methane VOC emissions.

Nighttime chemistry between NO₃ and BVOCs has received increased attention in the recent literature due to its potential influences on climate, air quality, health and visibility through the formation of many gaseous and particulate secondary pollutants such as organic nitrates, secondary organic aerosol (SOA), ozone and other functionalized products. In several studies conducted in clean forested environments, NO₃ concentrations were found to be very low, mostly below the detection limits (2-6pptv), which can be explained by the low concentrations of precursors (NO₂ and O₃) and the high reactivity of NO₃ with unsaturated BVOCs. However, significant contribution of NO₃-BVOC reactions to the secondary pollutants formation in these clean areas have been found.

Since NO₃ radicals are formed more rapidly in polluted air masses, it is expected that reactions with BVOCs are even more important in mixed atmospheres, i.e. influenced by both biogenic and anthropogenic sources and characterized by relatively high concentrations of both VOCs and NO₂. The ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) field campaign was carried out in June and July 2022 in Ile-de-France region and aims, among other objectives, to assess the potential impact of NO₃-BVOC nocturnal processes on SOA formation. For this purpose, a newly developed field instrument, called "NOyBox", was deployed on top of a 40-meter tower, which is above the canopy, located at the Rambouillet Forest supersite southwest of Paris. The instrument allows the measurement of NO₃ radicals, N₂O₅ and HONO (IBB-CEAS, Incoherent Broad Band Cavity Enhanced Absorption Spectroscopy), NO₂ (CAPS, Cavity Attenuated Phase Shift) and NO_y (gold heated converter coupled with a NO chemiluminescence analyzer). Significant concentrations of NO₃ and N₂O₅ were detected on several nights with situations characterized by air masses coming from the direction of Paris, high concentrations of ozone and NO_2, and moderate relative humidity levels. Concentrations of these species as well as concentrations of species of interest for NO₃ chemistry are presented and the resulting implications on nighttime chemistry are discussed.

How to cite: Harb, S., Cirtog, M., Cazaunau, M., Feingesicht, M., Michoud, V., Landsheere, X., Pangui, E., Alhajj Moussa, E., Berge, A., Cantrell, C., and Picquet-Varrault, B.: Nighttime concentrations of NO3 and N2O5 in mixed anthropogenic/biogenic air masses during the ACROSS campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-437, https://doi.org/10.5194/egusphere-egu23-437, 2023.

17:10–17:20

EGU23-8093

AS5.9

ECS

On-site presentation

Investigation of Organic Nitrates in a European Temperate Forest

Simone Andersen, Patrick Dewald, Laura Wüst, Tobias Seubert, Jan Schuladen, Gunther N. T. E. Türk, Lucy J. Carpenter, and John N. Crowley

Biogenic volatile organic compounds (BVOCs) are to a great extent oxidized by NO₃ radicals at night leading to the formation of organic nitrates and secondary organic aerosols (SOA), which have an impact on human health and air quality. One of the focus points of the ACROSS (Atmospheric ChemistRy Of the Suburban forest) campaign, which took place in a temperate forest influenced by emissions from Paris over a period of 6 weeks during the Summer of 2022, was nighttime chemistry between NO₃ radicals and BVOCs and its relative importance to daytime chemistry for organic nitrate formation.

Measurements of total alkyl and peroxy nitrates and NO₂ mixing ratios were performed using multi-channel cavity-ring-down spectroscopy (CRDS) with thermal dissociation inlets operated at different temperatures to distinguish between alkyl nitrates and peroxy-nitrates.

NO₂ were on average 1500 pptv across the entire campaign with an average diel maximum of 2200 pptv at nighttime and minimum of 800 pptv in the afternoon. Both total alkyl and peroxy nitrates showed a diel profile with average daytime maxima of 250 and 450 pptv, respectively, and average nighttime minima of 150 and 250 pptv, respectively.

The relative contributions of day- and nighttime chemistry for generation of ANs will be assessed as will the lifetime of ANs in this environment and the efficiency of NO_x conversion into organic nitrates.

How to cite: Andersen, S., Dewald, P., Wüst, L., Seubert, T., Schuladen, J., Türk, G. N. T. E., Carpenter, L. J., and Crowley, J. N.: Investigation of Organic Nitrates in a European Temperate Forest, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8093, https://doi.org/10.5194/egusphere-egu23-8093, 2023.

17:20–17:30

EGU23-7568

AS5.9

Highlight

On-site presentation

French ACROSS 2022 campaign – First results from CO2/H2O, energy and VOC fluxes measurements at the Rambouillet tower supersite

Pauline Buysse, Benjamin Loubet, Florence Lafouge, Alain Fortineau, Jeremie Depuydt, Raluca Ciuraru, Baptiste Esnault, Celine Decuq, Pedro-Henrique Herig-Coimbra, Mathis Lozano, Vincent Michoud, and Christopher Cantrell

Volatile organic compounds (VOC) contribute to the production of pollutants harmful to human health and the environment. Most VOC (90 %) are biogenic. At the European scale, forests account for 55 % of the total VOC emissions, crops 27 %, and grasslands, wetlands and shrubs 18 % (Karl, 2009). These estimates are hampered by lack of data acquired at the ecosystem scale. In this work we measured VOC fluxes above the mixed (oaks and pines) forest of Rambouillet (about 60 km south west of Paris) during the ACROSS 2022 summer campaign. The objectives were (1) to quantify emission and deposition of constitutive VOC, and those occurring in response to heat and drought stresses, and (2) to study VOC formation in the canopy.

VOC fluxes were measured at the top of a 40 m-tall tower located at the Rambouillet ACROSS super site. A PTR-Qi-TOF-MS was installed in a shelter at the foot of the tower, and the air sucked through a 50 m heated line by a high-volume pump to ensure short residence time. The PTR-MS was synchronised at 10 Hz with an ultrasonic anemometer to compute fluxes by eddy covariance. Additionally, VOC concentrations were measured along a 5-level profile between 2m and 40m. Preliminary results show emission and deposition of more than 80 VOC compounds. The forest at this location was a strong emitter of monoterpenes, but also of isoprene and sesquiterpenes. A heatwave event has led to a clear decrease in photosynthesis and transpiration during week 28. This period also corresponded to the highest emissions observed during the whole campaign. Deposition of heavy VOC compounds (m/z > 220) was also observed, possibly corresponding to nitrogen or sulphur containing compounds.

How to cite: Buysse, P., Loubet, B., Lafouge, F., Fortineau, A., Depuydt, J., Ciuraru, R., Esnault, B., Decuq, C., Herig-Coimbra, P.-H., Lozano, M., Michoud, V., and Cantrell, C.: French ACROSS 2022 campaign – First results from CO2/H2O, energy and VOC fluxes measurements at the Rambouillet tower supersite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7568, https://doi.org/10.5194/egusphere-egu23-7568, 2023.

17:30–17:40

EGU23-8905

AS5.9

ECS

Virtual presentation

Particle hygroscopicity in an urban background environment during the ACROSS campaign

Shravan Deshmukh, Laurent Poulain, Birgit Wehner, Jean-Eudes Petit, Pauline Fombelle, Oliver Favez, Hartmut Herrmann, and Mira Pöhlker

Hygroscopicity strongly influences aerosol particle properties and multiphase chemistry, which also plays an essential role in several atmospheric processes. Although CCN (cloud condensation nuclei) properties are commonly measured, sub-saturation hygroscopicity measurements remain rare. Within the ACROSS campaign, which took place in the Paris region, France, during the summer of 2022, the particle’s hygroscopic growth at 90 % relative humidity (RH) and chemical composition were concurrently measured using a Hygroscopicity Tandem Differential Mobility Analyser (HTDMA, scanning at 100, 150, 200, and 250 nm) and Aerodyne High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) respectively, at the ACTRIS (the European Aerosol, Clouds and Trace gases Research Infrastructure) SIRTA near facility, a peri-urban site representative of the Greater Paris background conditions. Growth factor probability density distributions (GF-PDF) show two distinct modes: hydrophobic and hygroscopic, indicating that the particles are internally and externally mixed. The hygroscopic mode is always more prominent in the GF-PDF, indicating a change in the particles' mixing state. The dominance of the hygroscopic mode becomes more pronounced with increasing particle size. The mean hygroscopicity parameter values, κ of 100, 150, 200, and 250 nm particles derived from hygroscopicity measurements are respectively 0.23, 0.29, 0.36, and 0.38 during the sampling period. The size dependence is reflected in the averaged values of κ and the GF distributions. A diurnal pattern was observed with an average daytime κ higher than during night-time, which could be linked to aging processes and secondary aerosol formation during the day. The Zdanovskii-Stokes-Robinson (ZSR) mixing rule was applied on the particle chemical to make accurate quantitative predictions of the mean GF of mixed atmospheric aerosol particles.

Keywords: Hygroscopicity, Growth factor, hygroscopicity parameter κ.

How to cite: Deshmukh, S., Poulain, L., Wehner, B., Petit, J.-E., Fombelle, P., Favez, O., Herrmann, H., and Pöhlker, M.: Particle hygroscopicity in an urban background environment during the ACROSS campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8905, https://doi.org/10.5194/egusphere-egu23-8905, 2023.

17:40–17:50

EGU23-17306

AS5.9

On-site presentation

Contrasting aerosol composition in and out of Paris plume during the ACROSS campaign at the Rambouillet supersite

Joel Ferreira de Brito, Paola Formenti, Sebastien Dusanter, Marina Jamar, Alexandre Tomas, Laurent Alleman, Esperanza Perdrix, Pablo Espina, Veronique Riffault, Chenjie Yu, Claudia Di Biagio, Aline Gratien, Ludovico Di Antonio, Lelia Hawkins, Barbara D'Anna, Julien Kammer, Anne Monod, Jean-Eudes Petit, Shravan Deshmukh, and Laurent Poulain and the ACROSS Leadership

Based on a combination of ground-sites and aircraft observations, the ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) project seeks to better understand how the pollution from Paris affects air quality over large regional scales, particularly through interaction with biogenic species. A field campaign took place in June-July 2022 at three sites: a forested remote site (Rambouillet, 50 km southwest from downtown Paris) a peri-urban (SIRTA) and an urban ones (PRG). The extensive instrumentation deployed at those sites allows to gain insights into the transformation of gaseous and particulate species from local to regional scales. Besides, the Rambouillet site has not only served as a receptor site from Paris plume but also led to detailed observations of freshly emitted biogenic compounds and their role in local chemistry, reactivity, and aerosol properties.

This work focuses on the real-time aerosol composition at the Rambouillet site. High resolution time-of-flight aerosol mass spectrometry sampled air from below (3 m above ground level) and above the canopy (40 m), and has been complemented by a suite of aerosol instruments including PTRMS-CHARON (targeting semi-volatile species above the canopy), and the PEGASUS mobile facility sampling below the canopy. Furthermore, data will be combined with SIRTA and PRG observations for case studies where Paris plume was transported into the supersite, or conversely, clean air masses were first observed at the remote site, and then advected towards the urban area. During the six-week observation period, the average PM₁ (non-refractory PM₁ + equivalent BC) was 8.4 µg m^-3, with significant variability (10^th-90^th percentiles of 2.3 and 17.9 µg m^-3). The dominant component was organics with an average contribution to PM₁ of 62%, and peak contribution during periods of warm temperature of up to 90%. The organic aerosol was fairly oxidized at the site (average O:C ratio of 0.6), as expected for such an environment, with a negative trend of oxidation with organic aerosol loading, indicating primary or relatively fresh particles contributing the most to polluted episodes. Secondary inorganic aerosols (sulfate, nitrate, and ammonium) represented about 34% of PM₁, with the highest contribution during cold, rainy periods, and equivalent BC only had a minor contribution of about 4%. This presentation aims at providing a large picture of aerosol composition in the Ile-de-France region during the ACROSS experiment.

Acknowledgments. This work is supported by the French national research agency (ANR-20-CE01-0010), the Labex CaPPA (ANR-11-LABX-005-01) and the French national program LEFE/CHAT INSU.

How to cite: Ferreira de Brito, J., Formenti, P., Dusanter, S., Jamar, M., Tomas, A., Alleman, L., Perdrix, E., Espina, P., Riffault, V., Yu, C., Di Biagio, C., Gratien, A., Di Antonio, L., Hawkins, L., D'Anna, B., Kammer, J., Monod, A., Petit, J.-E., Deshmukh, S., and Poulain, L. and the ACROSS Leadership: Contrasting aerosol composition in and out of Paris plume during the ACROSS campaign at the Rambouillet supersite, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17306, https://doi.org/10.5194/egusphere-egu23-17306, 2023.

17:50–18:00

EGU23-420

AS5.9

ECS

On-site presentation

Aerosol complex refractive index retrieval in the Paris urban area and its forested surroundings during the ACROSS field campaign: variability and constraint for direct radiative effect estimation in regional models

Ludovico Di Antonio, Claudia Di Biagio, Matthias Beekmann, Aline Gratien, Paola Formenti, Astrid Bauville, Antonin Bérge, Joel Ferreira de Brito, Mathieu Cazaunau, Servanne Chevaillier, Barbara D’Anna, David Owen De Haan, Olivier Favez, Cecile Gaimoz, Olivier Garret, Leila N. Hawkins, Julien Kammer, Brigitte Language, Franck Maisonneuve, Griša Močnik, Anne Monod, Gael Noyalet, Diana Pereira, Sebastien Perrier, Jean-Eudes Petit, Drew Pronovost, Véronique Riffault, Sydney Riley, Matthieu Riva, Marwa Shahin, Guillaume Siour, Brice Temime-Roussel, Chenjie Yu, Pascal Zapf, Gilles Foret, Jean-François Doussin, Christopher Cantrell, and Vincent Michoud

The complex refractive index (CRI) is one of the key parameter driving aerosol spectral optical properties and direct radiative effects (DRE). Its value and spectral variation under different conditions, such as anthropogenic− and biogenic−dominated environments and anthropogenic−biogenic mixing situations, remains not fully understood. As a consequence, oversimplified representations of aerosol optical properties are generally used in climate models. Therefore, measurements of aerosol CRI in different environments and their inclusion in models are needed. The field observations from the ACROSS campaign, performed in June-July 2022 in the Ile de France region, are used in this study to deepen the knowledge of aerosol optical properties, aiming to improve the aerosol representation in the CHIMERE model and provide the best constraint for DRE simulations. Measurements obtained both at the Paris city center and the Rambouilllet rural forest sites during ACROSS are considered, in order to explore the CRI variability from anthropogenic−dominated to biogenic−dominated environments, including anthropogenic−biogenic mixing situations. The CRI retrievals at seven different wavelengths, performed by combining the Mie theory with optical and size distribution measurements, are representative of different atmospheric conditions, aerosol loadings as well as type and chemical compositions. In fact, the June-July 2022 period was characterized by highly diversified weather conditions: 1) two strong heatwaves, promoting SOA build-up and favoring the export of the Paris pollution plume towards the forest site; 2) Saharan dust events transported from the upper atmosphere to the ground; 3) biomass burning episode; 4) periods with reduced anthropogenic influence. The CRI retrievals under these different conditions and their link to particulate chemical composition is investigated. Hence, the CRI dataset presented here constitutes a unique dataset from which models can benefit to validate and constrain simulations and DRE estimations, under both urban and biogenic emissions influence. These data, in conjunction with those from the aircraft observations during ACROSS, are used to initialize and perform sensitivity studies on the aerosol DRE, using the CHIMERE−WRF coupled model, the OPTSIM model for the aerosol optical properties and the Rapid Radiative Transfer Model for GCMs (RRTMG).

Keywords: Complex refractive index, direct radiative effect, aerosol mixing, urban, forest

How to cite: Di Antonio, L., Di Biagio, C., Beekmann, M., Gratien, A., Formenti, P., Bauville, A., Bérge, A., de Brito, J. F., Cazaunau, M., Chevaillier, S., D’Anna, B., De Haan, D. O., Favez, O., Gaimoz, C., Garret, O., Hawkins, L. N., Kammer, J., Language, B., Maisonneuve, F., Močnik, G., Monod, A., Noyalet, G., Pereira, D., Perrier, S., Petit, J.-E., Pronovost, D., Riffault, V., Riley, S., Riva, M., Shahin, M., Siour, G., Temime-Roussel, B., Yu, C., Zapf, P., Foret, G., Doussin, J.-F., Cantrell, C., and Michoud, V.: Aerosol complex refractive index retrieval in the Paris urban area and its forested surroundings during the ACROSS field campaign: variability and constraint for direct radiative effect estimation in regional models, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-420, https://doi.org/10.5194/egusphere-egu23-420, 2023.

Posters on site: Wed, 26 Apr, 14:00–15:45 | Hall X5

Chairpersons: Eleonora Aruffo, Valérie Gros, Christopher Cantrell

X5.193

EGU23-12435

AS5.9

Overview of the ACROSS Campaign near Paris in Summer 2022

Christopher Cantrell, Vincent Michoud, Jean-Francois Doussin, Paola Formenti, Manuela Cirtog, Patrice Coll, Ludovico Di Antonio, Claudia Di Biagio, Aline Gratien, Benedicte Picquet-Varrault, and Guillaume Siour and the ACROSS Measurement and Modeling Team

ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) is an integrative, innovative, multi-scale project within the “Make Our Planet Great Again” (MOPGA) initiative designed to advance understanding of the fate of the photochemical processing of urban and biogenic air mass mixtures in the Paris region. An ACROSS hypothesis is that the anthropogenic-biogenic air mass mixing leads to changes in the production of oxygenated volatile organic compounds (VOCs) whose properties alter their importance in incorporation into secondary organic aerosols (SOA) and their roles in production of ozone and other relevant secondary species. A likely important factor is NOx transport to suburban biogenic environments and the resulting modification of key chemical processes.

The key highlight of ACROSS was an intensive, multi-platform measurement campaign that took place in the summer of 2022. The campaign included measurements from multi-instrumented ground sites located in the urban, rural, and semi-rural Paris region including a 40-meter tower and from the ground in the Rambouillet suburban forest southwest of Paris, and airborne regional observations following the urban plume downwind of Paris and areas within 150 km (coordinated with other projects in the framework of the PANAME initiative). As the analysis proceeds, the data collected from this campaign will provide a unique snapshot of the properties that are characteristic of combinations of urban and biogenic air masses around one of the largest European megacities. This new knowledge will contribute to advancement of our understanding at the process level and will lead to the ability to better represent such complex systems in numerical models, ultimately resulting in improved capability to predict the impacts on air quality, regional climate, and global climate change.

This presentation consists of a summary of the campaign organization and measurements. Some preliminary findings from the analysis of the observations in the early stages are shown as a complement to other, more focused evaluations that are given at this meeting.

How to cite: Cantrell, C., Michoud, V., Doussin, J.-F., Formenti, P., Cirtog, M., Coll, P., Di Antonio, L., Di Biagio, C., Gratien, A., Picquet-Varrault, B., and Siour, G. and the ACROSS Measurement and Modeling Team: Overview of the ACROSS Campaign near Paris in Summer 2022, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-12435, https://doi.org/10.5194/egusphere-egu23-12435, 2023.

X5.194

EGU23-11676

AS5.9

ECS

In situ VOC measurements in the center of Paris under local biogenic influence ( Spring- Summer 2022)

Carmen Kalalian, Valérie Gros, Leïla Simon, Vincent Douet, Aurélien Faucheux, Christophe Boitel, Nathalie Bocquet, Julien Kammer, Barbara D'anna, Jean-Eudes Petit, Olivier Favez, Juliette Leymarie, and Christophe Boissard

It is generally acknowledged that urban vegetation improves the environmental quality of cities around the world as they can provide ecosystem services like mitigation of urban heat island effect, and capture of atmospheric pollutants by the leaf surfaces. However, vegetation is also a source of Biogenic Volatile Organic Compounds (BVOC), that can be targets of oxidants produced from chemical interactions with anthropogenic atmospheric pollutants. Such oxidation phenomena trigger the formation of secondary pollutants like ozone (O₃) and secondary organic aerosols (SOA). As part of the sTREEt (Impact of sTress on uRban trEEs and on city air quality) project, the present work aims to (i) characterize the ambient gaseous composition in the center of Paris (Town Hall) impacted by a local biogenic source (an urban garden and street trees) and subjected to significant anthropogenic contributions (mainly traffic), and (ii) estimate the contribution of BVOC (vs Anthropogenic VOC) and ultimately their impact on the ambient air quality (O₃, SOA). A field campaign took place in Paris city center, from June 8^th to July 6^th, 2022, notably including a heat wave period on June 17^th and 18^th(with temperature up to 37°C). The experimental set-up comprised continuous measurements of VOC (using PTR-ToF-MS), NO_x (as traffic tracer), aerosol chemical composition (using ACSM) and meteorological parameters (i.e., temperature, wind, light irradiation). VOCs speciation (including terpenes) was also performed off-line based on cartridges analyses for selected days. Results are presented and compared here with measurements at a suburban site at the SIRTA-ACTRIS facility (20 km SW of Paris).

The overall VOC concentrations at the town hall site were higher than at the SIRTA site. Furthermore, isoprene and monoterpenes were mainly of anthropogenic origin, with a diurnal variability and a strong correlation with traffic markers (NO_x and aromatic VOC). However, during the heat wave, the concentrations of isoprene and monoterpenes increased and showed a different variability than that of the traffic markers. The concentration of isoprene became very significant with levels around 6 ppb (comparable to the SIRTA site), due to the increase in the biotic component, which may promote the formation of ozone. On the other hand, the moderate increase in monoterpene concentrations (0.1 to 0.7 ppb), due as well to the increase in the biotic component, could contribute significantly to the SOA formation. Thus, assuming a near future increase in the frequency and intensity of heat waves, the contribution of the biogenic source to the ambient air quality may be even more important in urban areas with strong anthropogenic contributions.

How to cite: Kalalian, C., Gros, V., Simon, L., Douet, V., Faucheux, A., Boitel, C., Bocquet, N., Kammer, J., D'anna, B., Petit, J.-E., Favez, O., Leymarie, J., and Boissard, C.: In situ VOC measurements in the center of Paris under local biogenic influence ( Spring- Summer 2022), EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-11676, https://doi.org/10.5194/egusphere-egu23-11676, 2023.

X5.195

EGU23-3467

AS5.9

Highlight

Report on selected measurements in the canopy of a Rambouillet forest site during the ACROSS field campaign

Alexandre Kukui, Chaoyang Xue, Jérôme Houny, Max Mcgillen, Fanny Bachelier, Benoit Grosselin, Véronique Daële, and Wahid Mellouki

X5.196

EGU23-5240

AS5.9

ECS

First ground-deployment of a new small-footprintcavity-ring-down spectrometer for NO3 and N2O5 in a temperate forest during the ACROSS campaign

Gunther N. T. E. Türk, Simone T. Andersen, Patrick Dewald, Jan Schuladen, Tobias Seubert, and John N. Crowley

At nighttime, when concentrations of the OH-radical are low, the nitrate radical, NO₃, over takes the role of major initiator of the oxidation of many organic trace gases, especially those containing one or more double bonds. In contrast to daytime, where the lifetime of NO₃ is very short due to its photolysis and reaction with NO, NO₃ can reach mixing ratios of several tens of ppt at night. NO₃ can also react with NO₂ to form N₂O₅. As N₂O₅ is thermally stable, the three trace-gases usually exist in equilibrium:

NO₃ + NO₂ + M ⇌ N₂O₅ + M

Measurements of NO₃ and N₂O₅ are central to our understanding of the fate of NO_x at night. Loss of NO₃ to gas-phase reactions (forming e.g. organic nitrates) has a different impact on NO_x than formation of N₂O₅ which may hydrolyse on aerosol to form particulate nitrate.

During the ACROSS campaign in Rambouillet Forest (France), a recently built two-channel cavity-ring-down spectrometer was deployed for the first time to record mixing ratios of NO₃ and N₂O₅ at night over a period of several weeks. NO₃ was detected directly at 662nm in one channel while N₂O₅ was first converted to NO₃ in a thermal dissociation inlet before being detected in the same way.

In this work, we describe the new instrument in detail and compare obtained data with those measured by an established cavity-ring-down instrument. We show that, at a sampling height of about 6m, NO₃ and N₂O₅ mixing ratios were low and frequently below the detection limit of both instruments; the likely reasons for this are discussed.

How to cite: Türk, G. N. T. E., Andersen, S. T., Dewald, P., Schuladen, J., Seubert, T., and Crowley, J. N.: First ground-deployment of a new small-footprintcavity-ring-down spectrometer for NO3 and N2O5 in a temperate forest during the ACROSS campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5240, https://doi.org/10.5194/egusphere-egu23-5240, 2023.

X5.197

EGU23-5061

AS5.9

ECS

NO3 reactivity in a temperate forest impacted by anthropogenic and biogenic emissions during the ACROSS campaign

Patrick Dewald, Simone T. Andersen, Gunther N.T.E. Tuerk, Jan Schuladen, Tobias Seubert, and John N. Crowley

Terpenoids are readily released into the environment via biogenic emissions. One of their major nighttime oxidizing agent is the nitrate radical (NO₃), which is formed from the reaction between ozone (O₃) and nitrogen dioxide (NO₂). The NO₃-initiated oxidation of such biogenic volatile organic compounds (BVOCs) leads to the formation of organic nitrates that can deposit on particles to form secondary organic aerosols. This reaction path thus can lead to irreversible removal of NO₂, usually of anthropogenic origin, from the gas phase. Alternatively, NO₃ rapidly reacts with nitric oxide (NO) with reformation of NO₂. Assigning the contribution of BVOCs and NO to the NO₃ reactivity therefore provides insight into the fate of NO_x (= NO + NO₂).

We used a flow-tube coupled to a cavity-ring-down spectrometer (FT-CRDS) to make direct measurements of the NO₃reactivity in air (at a height of ~ 6 m above ground level) during the ACROSS field campaign in the forest of Rambouillet in the vicinity of Paris, France. Measured reactivities ranged from < 0.006 s^-1 to 2.3 s^-1, with high average daytime and nighttime reactivities of 0.13 s^-1 and 0.25 s^-1, respectively. In addition, vertical profiles of NO₃ reactivity (up to 40 m) were made and are compared to data previously observed in a boreal forest. Reactivities in Rambouillet forest were highest close the ground (0.36 s^-1at 0 m) and drastically decreased with height (0.08 s^-1 at 24 m).

By comparing direct NO₃ reactivity measurements with those calculated from trace gas mixing ratios and their corresponding rate coefficients, we identify the contributions of BVOCs and NO to NO₃ losses.

How to cite: Dewald, P., Andersen, S. T., Tuerk, G. N. T. E., Schuladen, J., Seubert, T., and Crowley, J. N.: NO3 reactivity in a temperate forest impacted by anthropogenic and biogenic emissions during the ACROSS campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5061, https://doi.org/10.5194/egusphere-egu23-5061, 2023.

X5.198

EGU23-3503

AS5.9

ECS

Field measurements of organic and inorganic composition in the Rambouillet Forest during ACROSS campaign

Fanny Bachelier, Chaoyang Xue, Jérôme Houny, Max McGillen, Alexandre Kukui, Benoit Grosselin, Abdelwahid Mellouki, and Véronique Daële

Rambouillet Forest is a large forested location, situated about 50km from central Paris. It covers some 200km² and contains mainly a mix of oak and pine trees. Its size and proximity towards Paris makes it an interesting site to study the interaction between polluted air masses and biogenic emissions and the impact on air quality in areas surrounding polluted cities. The ACROSS (Atmospheric ChemistRy Of the Suburban forest) campaign represents a large international collaboration between various French, European and American institutes, which aims to further characterize these interactions. For our contribution, different instruments from ICARE and LPC2E CNRS Orléans performed in-situ measurements in this forest during June and July of 2022, including: VOCs/ BVOCs (GC-MS/FID); oxidants (OH radicals, CIMS); oxidant precursors (NOx, NOy, Ecophysics, CAPS, LOPAP); and highly oxidized products (orbitrap). In general, data coverage for all instrumentation was high throughout the campaign, furthermore this instrumentation was calibrated and characterized under field condition where possible. These observations represent a broad look at the composition of the forested environment, and contain information on organic emissions, their oxidized products, oxidants and oxidant precursors. We therefore anticipate that these measurements will contribute significantly to the understanding of the atmospheric chemistry operating during the ACROSS campaign.

How to cite: Bachelier, F., Xue, C., Houny, J., McGillen, M., Kukui, A., Grosselin, B., Mellouki, A., and Daële, V.: Field measurements of organic and inorganic composition in the Rambouillet Forest during ACROSS campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-3503, https://doi.org/10.5194/egusphere-egu23-3503, 2023.

X5.199

EGU23-17469

AS5.9

ECS

Presence of siloxanes in the ambient air of urban Paris during the ACROSS field campaign

Rulan Verma, Sebastien Perrier, Vincent Michoud, Claudia Di Biagio, Aline Gratien, Lelia Hawkins, Barbara D'Anna, Julien Kammer, Anne Monod, Christopher Cantrell, Christian George, and Matthieu Riva

Cyclic volatile methyl Siloxanes (cVMS) are a group of silicon-based organic compounds of anthropogenic origin that are found ubiquitously in the ambient air. They find wide application in many industrial, automotive products, consumer, and personal care products such as paints, solvents, adhesives, cosmetics, polymers, etc. About 90% of the environmentally released cyclic siloxanes diffuse directly into the atmosphere. They are high–production volume chemicals with some having an annual production rate of 45 to 227 thousand tons worldwide. Siloxanes have been observed in both urban and rural areas. Among the different siloxanes emitted into the atmosphere hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5) are of great importance due to their subsequent concentrations. It should be mentioned that siloxanes are not readily biodegradable which means they can persist in the environment for a long duration. The D4 species has already been identified as a potential persistent organic pollutant (PoPs). D4 and D5 are very persistent and bioaccumulative and have evinced or potential hazards to both humans and the environment.

Taking advantage of the Vocus proton-transfer-reaction time-of-flight mass spectrometer (VOCUS PTR–TOF–MS) the D3, D4, and D5 species were measured in real-time downtown Paris in the June–July 2022 period. The measurements were performed during the ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) field campaign at the urban site located at Université Paris Cité (48.83°N, 2.38°E) sampling at about 25 m above the ground level. The data collected during the summer 2022 showed that the mean concentrations were 0.099±0.009, 0.045±0.009, and 0.131±0.089 ppb for D3, D4, and D5, respectively. A strong diurnal cycle was observed for the different siloxanes. Concentrations for the D5 siloxane peaked in the morning with an averaged maximum of 0.298± 0.119 ppb while the 25^th and the 75^th quantile are 0.221 and 0.377 ppb, respectively. In the afternoon concentrations show a minimum value, followed by a slight increase during the night. The D5 is the most abundant siloxane species and shows the strongest diurnal cycle compared to the other two identified siloxanes. Observations during the campaign and the potential reaction products and sources of siloxanes will be discussed in this work.

KEYWORDS: Siloxanes; Cyclic Siloxanes; D3,D4 and D5; Ambient Air; PoPs; ACROSS; HR- Mass Spectrometry; VOCUS PTR-Tof

How to cite: Verma, R., Perrier, S., Michoud, V., Di Biagio, C., Gratien, A., Hawkins, L., D'Anna, B., Kammer, J., Monod, A., Cantrell, C., George, C., and Riva, M.: Presence of siloxanes in the ambient air of urban Paris during the ACROSS field campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17469, https://doi.org/10.5194/egusphere-egu23-17469, 2023.

X5.200

EGU23-17525

AS5.9

ECS

Organic particles and gaseous precursors in suburban Paris during the ACROSS campaign in summer 2022: first deployment of a PTR-ToF-MS coupled with CHARON at the SIRTA observatory

Etienne Brugère, Shravan Deshmukh, Aurélie Lambreschi, Leïla Simon, Carmen Kalalian, Nicolas Bonnaire, Aurélie Colomb, Evelyn Freney, Valérie Gros, Jean-Eudes Petit, Laurent Poulain, Mickaël Ribeiro, Junteng Wu, and Agnès Borbon

Atmospheric organic aerosols (OA) are important because of their ubiquity and significance. They are the key drivers of air quality and climate change. While the secondary fraction of OA, namely SOA, is dominant in mass (between 50 to 85%), our capability to predict SOA is still uncertain because of the influence of multiple parameters (ie. humidity, temperature, NOx, nature and vapor pressure of organic gaseous precursors). Quantifying the partitioning between the gas and particle phases of semi-volatile organic compounds (SVOCs) in real conditions is one relevant approach to better constraint the budget of SOA and to develop accurate parametrization for organic aerosol formation in climate models.

During the summer of 2022, the ACROSS field campaign (Atmospheric ChemistRy Of the Suburban foreSt) took place in the Paris region at several sites located along a southwest to northeast transect for a comprehensive characterization of the gaseous and particulate atmospheric composition. For the first time, a PTR-ToF-MS (Proton Transfer Reaction-Time of Flight Mass Spectrometry) coupled with a CHARON (Chemical Analysis of aeRosol ON-line) inlet as part of the MOCCA set-up (Mass spectrOmetry for the multiphasic Composition of the Cloudy Atmosphere) was deployed at the SIRTA observatory. SIRTA is a suburban site being part of the Aerosols, Cloud, and Trace gases Research InfraStructure (ACTRIS), where long-term monitoring of in-situ reactive gases and particles has been performed for more than a decade [Simon et al. 2022]. Such deployment is a unique opportunity to qualify and intercompare the technical performances of the CHARON-PTR-ToF-MS system with other state of the art instrumentation at the site [Petit et al. 2015/Zhang et al., 2019] (PTR-Q-MS, quadrupole Aerosol Chemical Speciation Monitor (Q-ACSM), Scanning Mobility Particle Sizer (SMPS), Condensation Particle Counter (CPC)), or aerosol size spectrometer for PM-10 and PM-2.5 and also a High-Resolution Time-of-Flight Aerosol Mass Spectrometer (HR-ToF-AMS) by TROPOS institute.

In this work, I will present the technical evaluation of the CHARON-PTR-ToF-MS system with respects to other conventional mass spectrometry methods such as the ACSM, under both controlled laboratory conditions and ambient conditions. Using the unique features of the CHARON-PTR-ToF-MS system, it will consider the analysis of the temporal variability of trace gases and aerosol observations, meteorology and air mass trajectories, relevant and contrasting periods, thus, the partitioning between the particle phase and the gaseous phase could be estimated. These observations will be compared to collocated measurements of trace gases and aerosols and will be used to evaluate model predictions using equilibrium partitioning theory.

References :

Petit, J.-E., et al..: Two years of near real-time chemical composition of submicron aerosols in the region of Paris using an Aerosol Chemical Speciation Monitor (ACSM) and a multi-wavelength Aethalometer, Atmos. Chem. Phys., 15, 2985–3005, https://doi.org/10.5194/acp-15-2985-2015, 2015.

Simon, L., et al.: Two years of Volatile Organic Compounds online in-situ measurements at SIRTA (Paris region, France) using Proton-Transfer-Reaction Mass Spectrometry, Earth Syst. Sci. Data Discuss. [preprint], https://doi.org/10.5194/essd-2022-406, in review, 2022.

Zhang, Y., et al., A.: Six-year source apportionment of submicron organic aerosols from near-continuous highly time-resolved measurements at SIRTA (Paris area, France), Atmos. Chem. Phys., 19, 14755–14776, https://doi.org/10.5194/acp-19-14755-2019, 2019.

How to cite: Brugère, E., Deshmukh, S., Lambreschi, A., Simon, L., Kalalian, C., Bonnaire, N., Colomb, A., Freney, E., Gros, V., Petit, J.-E., Poulain, L., Ribeiro, M., Wu, J., and Borbon, A.: Organic particles and gaseous precursors in suburban Paris during the ACROSS campaign in summer 2022: first deployment of a PTR-ToF-MS coupled with CHARON at the SIRTA observatory, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-17525, https://doi.org/10.5194/egusphere-egu23-17525, 2023.

X5.201

EGU23-763

AS5.9

ECS

Highlight

Airborne measurement of aerosol physicochemical properties along the Paris urban plume

Chenjie Yu, Paola Formenti, Peter DeCarlo, Eleonora Aruffo, Piero Di Carlo, Edouard Pangui, Mathieu Cazaunau, Diana L. Pereira, Kevin Tu, Astrid Bauville, Grégoire Cayez, Noel Grand, Pascal Zapf, Vincent Michoud, and Christopher Cantrell

Atmospheric aerosols make significant contributions to several atmospheric chemical and physical processes. Aerosols from anthropogenic emissions have negative impact on air quality and human health. In recent years, significant progress has been made in understanding the anthropogenic pollutants. However, it is still not clear how mixtures of anthropogenic and biogenic emissions impact the regional climate and human health. To better understand aerosol physicochemical properties within the Paris urban plume when mixed with biogenic emissions, a comprehensive airborne measurement platform was deployed in the Île-de-France region in summer 2022 as part of the ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) campaign. In this study, the vertical and spatial distributions of aerosol chemical composition, size distributions, and optical properties during urban plume aging are characterized based on couples of in-situ measurement techniques like aerosol mass spectrometer (c-ToF-AMS), Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) and AVIRAD staged onboard the Safire ATR 42 research aircraft. Gas phase components are also detailed characterized by Proton-transfer-reaction mass spectrometry (PTR-ToF-MS) to act as tracers of anthropogenic and biogenic emissions. Based on gas and particulate phase organic information provided by laser-induced fluorescence technique (TDLIF), the production rate of particulate organic nitrate (pON) can also be estimated. These detailed airborne measurements of aerosol properties provide data that can contribute to modelling studies of aerosol characteristics.

How to cite: Yu, C., Formenti, P., DeCarlo, P., Aruffo, E., Di Carlo, P., Pangui, E., Cazaunau, M., L. Pereira, D., Tu, K., Bauville, A., Cayez, G., Grand, N., Zapf, P., Michoud, V., and Cantrell, C.: Airborne measurement of aerosol physicochemical properties along the Paris urban plume, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-763, https://doi.org/10.5194/egusphere-egu23-763, 2023.

X5.202

EGU23-7865

AS5.9

Highlight

Hygroscopic and optical properties of complex aerosol mixtures at the Rambouillet forest super-site of the ACROSS project

Paola Formenti and the ACROSS/Rambouillet aerosol team

The ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) project is an integrative and innovative large-scale initiative that seeks to definitively improve the understanding of the impacts of mixing urban and biogenic air masses in the largest Paris area (the Île-de-France region), where the Paris anthropogenic emissions and the biogenic emissions from the forested surroundings give rise to the coexistence of several particulate and gaseous species. This scheme promotes the formation of complex mixtures and also influences the physico-chemical aging of aerosol plumes, with consequences on the optical and hygroscopic properties of aerosols, and ultimately on their impacts. Representing the physico-chemical properties, distribution and radiative effect of aerosols at the regional scale of Ile de France is a challenge, limiting our ability to provide reliable climate projections.

ACROSS is based on a multiple platform intensive measurement campaign which was held in June-July 2022. In this paper, we present the first results of the ground-based observations of the aerosol hygroscopic and optical properties at the ACROSS supersite within the downwind Rambouillet forest, located on the south-west of Paris. Here, the PEGASUS (PortablE Gaz and Aerosol Sampling UnitS) mobile facility was operated to deploy an HTDMA (humidified tandem differential mobility analyser) to measure the size-resolved aerosol hygroscopic properties, and a suite of optical analysers including a spectral aethalometer (Magee sci model AE33), a spectral nephelometer (TSI Inc model 3596), and three CAPS-type instruments (Aerodyne Inc, models PMEx and SSA) to measure the particle absorption, scattering and extinction coefficients at wavelengths ranging between 370 and 950 nm. The HDTMA was set to operate primarily at 85% relative humidity. . The observational period was characterised by variable conditions ranging from clean to very polluted depending on the weather. The surface mass concentrations of submicron particles varied between 2 and 15 µg m-3 through the experimental campaign. The aerosol single scattering albedo at 450 nm varied between 0.88 and 1 during the campaign, the lowest values being observed during the heatwave period between 15 and 22 June when the aerosol optical depth reached 0.5 at 440 nm. The size growth factor (GF) for particles of 200 nm varied between 1 and 2 depending on air mass type and time of the day. The observations will be linked to the aerosol chemical composition and aerosol mixing state also observed during the campaign.

How to cite: Formenti, P. and the ACROSS/Rambouillet aerosol team: Hygroscopic and optical properties of complex aerosol mixtures at the Rambouillet forest super-site of the ACROSS project, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-7865, https://doi.org/10.5194/egusphere-egu23-7865, 2023.

X5.203

EGU23-493

AS5.9

ECS

Addressing the chemical composition of secondary organic aerosol in the rural/ urban Paris area

Diana L Pereira, Aline Gratien, Chiara Giorio, Gael Noyalet, Servanne Chevaillier, Thomas Bertin, Emmanuelle Mebold, Christopher Cantrell, Vincent Michoud, Claudia Di Biagio, Bénédicte Picquet-Varrault, Lelia Hawkins, Olivier Favez, Olivier Garret, Drew Pronovost, Ludovico Di Antonio, Joel F. de Brito, Véronique Riffault, Chenjie Yu, and Paola Formenti

Organic aerosol (OA) from natural or anthropogenic origin can be directly emitted into the atmosphere (primary organic aerosols, POA) or formed by secondary processes via the oxidation of volatile organic compounds (VOC). However, the formation pathways and their chemical composition of these secondary organic aerosols (SOA), which may contribute up to 90% of the OA mass, are not well understood to date, which is problematic due to the relevance of SOA on climate. To address this issue, this study uses a tracer-based approach to identify and quantify the contribution of different anthropogenic/biogenic VOCs precursors to the SOA formation. To do so, we combine experiments in a large scale atmospheric simulations chamber, CESAM (which means Multiphase Atmospheric Experimental Simulation Chamber), and field measurements during the ACROSS (Atmospheric ChemistRy Of the Suburban foreSt) campaign conducted in the Paris area in summer 2022. This approach provides both a mechanistic study of the oxidation of targeted VOCs in simulated and controlled rural/urban atmospheres and the identification of targeted tracers in the real atmosphere, to quantify their concentrations in ambient air.

The ACROSS dataset consists in atmospheric samples of submicron aerosols collected twice a day (day and night) in the urban area of Paris and the Rambouillet forest on the south-west of Paris, as well as samples collected onboard the Safire ATR-42 research aircraft on low-level flights targeting the evolution and dilution of the Paris urban plume. The CESAM chamber dataset consists in samples of SOA generated by the OH oxidation of toluene/ m-xylene in various conditions.

Filters are analyzed to provide with the chemical composition at the molecular scale by SFE-GC-MS (Supercritical Fluid Extraction Gas Chromatography- Mass Spectrometry) and UPLC-QTOF-MS (Ultra Performance Liquid Chromatography Time of Flight Mass Spectrometry). The organic mass and chemical speciation are obtained by aerosol mass spectrometry and the organic carbon (OC) concentrations by thermal-optical analysis.

The first results of the ambient samples of Paris revealed that the OC concentration varied between 0.69 ± 0.07 and 9.48 ± 0.51 µgC/m³, which correspond to the 28% and 53% of the total mass of the submicron aerosols, for background and polluted (fire) conditions, respectively. These diverse conditions are favorable to trace the compounds identified during the simulation chamber experiments, such as benzoic acid, succinic acid, and 2-methyl-4-nitrophenol. These attempts will be presented and discussed in order to determine the contribution of specific precursors to SOA formation.

How to cite: Pereira, D. L., Gratien, A., Giorio, C., Noyalet, G., Chevaillier, S., Bertin, T., Mebold, E., Cantrell, C., Michoud, V., Di Biagio, C., Picquet-Varrault, B., Hawkins, L., Favez, O., Garret, O., Pronovost, D., Di Antonio, L., F. de Brito, J., Riffault, V., Yu, C., and Formenti, P.: Addressing the chemical composition of secondary organic aerosol in the rural/ urban Paris area, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-493, https://doi.org/10.5194/egusphere-egu23-493, 2023.

X5.204

EGU23-15788

AS5.9

Forest fire plumes in the Paris region (France) during summer 2022, the spoor of a schorching summer

Jean-Eudes Petit, Valérie Gros, Olivier Favez, Leila Simon, Carmen Kalalian, Etienne Brugère, Agnès Borbon, Jean-Charles Dupont, Grégory Abbou, Véronique Ghersi, Vincent Michoud, Claudia Di Biagio, Paola Formenti, Christopher Cantrell, Aline Gration, Joêl Brito, Sebastien Dusanter, Marina Jamar, and Martial Haeffelin

In the context of climate change with increasingly pronounced impacts, year 2022 in France has been the warmest year ever observed. It has been the case more specifically during July, when a severe heatwave occurred across North-Western Europe. Sea-level temperature anomalies jumped over +12°C, especially in the Western half of France, pushing back all-time records. Associated to extreme temperature occurred a severe drought, with long-lasting precipitation deficit throughout the year, which was amplified during July. With around 80% deficit, July 2022 in France has also been the driest ever recorded. These singular meteorological conditions were therefore a fertile ground for forest fires. Around 70 000 ha of forest have burned in France during 2022. The South-West region has been particularly impacted during July 2022, as well as other areas which are not usually subject to this kind of events (Brittany, Center, Paris region).

During July 2022 occurred the ACROSS field campaign within the Paris region, where several sites following a South-West to North-East transect provided comprehensive characterization of atmospheric composition. Namely Rambouillet station (forest, SW of Paris), SIRTA (peri-urban, SW of Paris), PRG (urban, Paris center) and Chatelet Les Halles (urban, Paris center). These sites were equiped with state-of-the-art instrumentations to characterize aerosols and reactive gases. On July 19^th, an intense biomass burning plume went through the Paris region, with PM10 concentrations reaching more than 150µg/m³. The experimental effort during that period is therefore a unique asset in order to characterize the composition of this episode.

Most of the sites, during that episode, record high concentrations of carbonaceous aerosols (organic matter and black carbon) and Volatile Organic Compounds tracers of biomass burning (eg acetonitrile, benzene, toluene). Temporality of the episode, atmospheric dynamics and air mass pathways, suggest the transport of a biomass burning plume from South-Western France, more than 600km away from Paris. However, aerosol size distribution surpringly reveals the influence of local fires occuring near some of the sites, at almost the same time. This work is therefore focusing on the different properties of different plumes mixing at the same time over a densely urbanized region. These differences can be highlighted by source apportionment, combined with size distribution, as well as oxydation state of organic aerosols.

How to cite: Petit, J.-E., Gros, V., Favez, O., Simon, L., Kalalian, C., Brugère, E., Borbon, A., Dupont, J.-C., Abbou, G., Ghersi, V., Michoud, V., Di Biagio, C., Formenti, P., Cantrell, C., Gration, A., Brito, J., Dusanter, S., Jamar, M., and Haeffelin, M.: Forest fire plumes in the Paris region (France) during summer 2022, the spoor of a schorching summer, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-15788, https://doi.org/10.5194/egusphere-egu23-15788, 2023.

X5.205

EGU23-8457

AS5.9

ECS

Three-dimensional distribution of anthropogenic and natural aerosols over France measured using TROPOMI satellite observations during the ACROSS campaign

Prem Maheshwarkar, Juan Cuesta, Paola Formenti, Chenjie Yu, Farouk Lemmouchi, and Christopher Cantrell

ACROSS is an extensive field campaign that was conducted over the greater Paris region in summer 2022 to study the interaction between the urban pollution plume and biogenic volatile organic compounds emitted from the surrounding forests. This is mainly done by synergism of in-situ ground-based and airborne observations of the composition of the atmosphere (Cantrell and Michoud, 2022). Satellite observations are complementary to these measurements, providing a regional and continental framework of the atmospheric composition.

In this study, we present new satellite observations of the 3D distribution of anthropogenic and natural atmospheric aerosols over France during the ACROSS campaign. For this, we use a so-called AEROS5P approach which derives vertical profiles of aerosol extinction for each cloud free TROPOspheric Monitoring Instrument (TROPOMI) pixel using hyperspectral top of atmosphere (TOA) reflectance measurements in the visible and near infrared. This method uses a priori knowledge on particle properties, such as their size and refractive index, along with meteorological parameters from meteorological analyses (ECMWF), surface albedo properties, and a unique a priori aerosol vertical profile. The initial version of AEROS5P was able to monitor the 3D distribution of biomass burning aerosols over Australia, which is a single aerosol type (Lemmouchi et al., 2022).

In this study, we present a new version of AEROS5P for deriving the 3D distribution of several aerosol types present in the same atmospheric scene, from both anthropogenic and natural origins. This is done by taking for each TROPOMI pixel the co-localised aerosol type from the VIIRS aerosol product and then processing it with an associated aerosol model of microphysical and optical properties. These aerosol properties are taken from an AERONET sun photometer inversion climatology (Dubovik et al., 2002). This new multi aerosol type AEROS5P method is used for studying dust transport from North Africa, urban pollution from the Paris region, and smoke aerosol transport from South France during the ACROSS campaign. These results are compared against total aerosol extinction from MODIS, vertical aerosol backscatter from CALIOP, airborne and ground-based measurements of aerosol composition, optical and microphysical properties performed in the framework of ACROSS.

References

Cantrell, Christopher, and Vincent Michoud. "An Experiment to Study Atmospheric Oxidation Chemistry and Physics of Mixed Anthropogenic–Biogenic Air Masses in the Greater Paris Area." Bulletin of the American Meteorological Society 103.8 (2022): 599-603.

Dubovik, Oleg, et al. "Variability of absorption and optical properties of key aerosol types observed in worldwide locations." Journal of the atmospheric sciences 59.3 (2002): 590-608

Lemmouchi, Farouk, et al. "Three-Dimensional Distribution of Biomass Burning Aerosols from Australian Wildfires Observed by TROPOMI Satellite Observations." Remote Sensing 14.11 (2022): 2582.

How to cite: Maheshwarkar, P., Cuesta, J., Formenti, P., Yu, C., Lemmouchi, F., and Cantrell, C.: Three-dimensional distribution of anthropogenic and natural aerosols over France measured using TROPOMI satellite observations during the ACROSS campaign, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-8457, https://doi.org/10.5194/egusphere-egu23-8457, 2023.

X5.206

EGU23-4813

AS5.9

ECS

Air pollution in rural India: Analysis of satellite NO2 measurements

Mansi Pathak and Jayanarayanan Kuttippurath

India is a country having more than 67% of its population (947 million) residing in rural areas as of 2020. Therefore, health of the people in rural India becomes important for development plans, economy and growth of the nation. As the sources of NO₂ are closely linked to the industrial and economic development of a country, we use satellite measurements of NO₂ in rural and urban areas of India to analyse the air quality in these areas. Our findings for rural areas show strong seasonal variations, with winter having the highest NO₂(2.0×10¹⁵molec./cm²) whereas monsoon having the lowest (1.5×10¹⁵molec./cm²) levels. Around 40% of the total NO₂pollution comes from rural sources with 45% of it attributed to road transport, however urban areas with more than 90% of their NO₂ from power sector were focused in the past studies. Our assessment shows that the NO₂ exposure in rural regions is as severe as in urban areas; indicating the need for more effective reduction measures of population exposure and protection of public health. Henceforth, this study reveals that rural India is gradually getting polluted from its nearby regions as well as from the new sources within, which is a big concern for the health of the large rural population of India.

How to cite: Pathak, M. and Kuttippurath, J.: Air pollution in rural India: Analysis of satellite NO2 measurements, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-4813, https://doi.org/10.5194/egusphere-egu23-4813, 2023.

X5.207

EGU23-5065

AS5.9

ECS

IAQMS-street v2.0: a two-way coupled regional-urban–street-network model system for Beijing, China

Tao Wang, Jie Li, Youngseob Kim, and Zifa Wang

Owing to the substantial traffic emissions in urban areas, especially near road areas, the concentrations of pollutants, such as ozone (O₃) and its precursors, have a large gap with the regional averages and their distributions cannot be captured accurately by traditional single-scale air-quality models. In this study, a new version of a regional-urban-street-network model (IAQMS-street v2.0) is presented. An upscaling module is implemented in IAQMS-street v2.0 to calculate the impact of mass transfer to regional scale from street network. The influence of pollutants in street network is considered in the concentration calculation on regional scale, which is not considered in a previous version (IAQMS-street v1.0). In this study, the simulated results in Beijing during August 2021 by using IAQMS-street v2.0, IAQMS-street v1.0, and the regional model (NAQPMS) are compared. On-road traffic emissions in Beijing, as the key model-input data, were established using intelligent image-recognition technology and real-time traffic big data from navigation applications. The simulated results showed that the O₃ and nitrogen oxides (NO_x) concentrations in Beijing were reproduced by using IAQMS-street v2.0 both on regional scale and street scale. The prediction fractions within a factor of two (FAC2s) between simulations and observations of NO and NO₂ increased from 0.11 and 0.34 in NAQPMS to 0.78 and 1.00 in IAQMS-street v2.0, respectively. The normalized mean biases (NMBs) of NO and NO₂ decreased from 2.67 and 1.33 to -0.25 and 0.08. the concentration of NO_x at street scale is higher than that at the regional scale, and the simulated distribution of pollutants on regional scale was improved in IAQMS-street v2.0 compared with that in IAQMS-street v1.0. We further used the IAQMS-street v2.0 to quantify the contribution of local on-road traffic emissions to the O₃ and NO_x emissions and analyze the effect of traffic-regulation policies in Beijing. Results showed that heavy-duty trucks are the major source of on-road traffic emissions of NO_x. The relative contributions of local traffic emissions to NO₂, NO, and O₃ emissions were 53.41, 57.45, and 8.49%, respectively. We found that traffic-regulation policies in Beijing largely decreased the concentrations of NO_xand hydrocarbons (HC); however, the O₃ concentration near the road increased due to the decrease consumption of O₃ by NO. To decrease the O₃ concentration in urban areas, controlling the local emissions of HC and NO_x from other sources requires consideration.

How to cite: Wang, T., Li, J., Kim, Y., and Wang, Z.: IAQMS-street v2.0: a two-way coupled regional-urban–street-network model system for Beijing, China, EGU General Assembly 2023, Vienna, Austria, 23–28 Apr 2023, EGU23-5065, https://doi.org/10.5194/egusphere-egu23-5065, 2023.