Preprints
https://doi.org/10.5194/egusphere-2024-2062
https://doi.org/10.5194/egusphere-2024-2062
22 Jul 2024
 | 22 Jul 2024

New Particle Formation Events Observed during the COALA-2020 Campaign

Jhonathan Ramirez-Gamboa, Clare Paton-Walsh, Melita Keywood, Ruhi Humphries, Asher Mouat, Jennifer Kaiser, Malcom Possell, Jack Simmons, and Travis Naylor

Abstract. Aerosols play an important role in atmospheric processes influencing cloud formation, scattering and absorbing solar radiation, and as a part of the chemical reactions affecting the abundance of trace gases in the atmosphere. Ultimately aerosols affect the radiative balance of the earth modifying climate. A large fraction of aerosols is formed through chemical reactions following gas-to-particulate processes in the atmosphere: nucleation, condensation and growth. Biogenic Secondary Organic Aerosols (BSOA) are formed when plant produced volatile organic compounds (VOCs) react in the atmosphere through heterogeneous reactions. South-east Australia is one of the locations with the highest emissions of biogenic VOCs in the world, due to the high density of Eucalyptus species, which are high emitters of VOCs. The COALA-2020 (Characterizing Organics and Aerosol Loading over Australia) campaign worked towards a better understanding of biogenic VOCs in quasi-pristine conditions in the atmosphere and their role in particle formation.

The observations showed a highly reactive atmosphere with frequent new particle formation occurring (50 % days with data) often associated with pollution plumes. Analysis of NPF events indicated that SO₂ and NOx plumes triggered particle formation, while particle growth depended on available VOCs, OH concentration (influenced by relative humidity), and the presence of multiple SO₂ and NOx intrusions promoted growth of smaller clusters. Nighttime NPF events correlated with NOx but the limited night-time data hindered conclusive interpretations. These findings highlight the significant role of biogenic VOCs, especially isoprene, in driving NPF and SOA formation in South-east Australia, even after major wildfires. The COALA-2020 campaign provided valuable insights into local atmospheric chemistry and its potential impact on regional air quality and climate. However, longer-term observations are crucial to understand seasonal variations, trends and extreme events.

Publisher's note: Copernicus Publications remains neutral with regard to jurisdictional claims made in the text, published maps, institutional affiliations, or any other geographical representation in this paper. While Copernicus Publications makes every effort to include appropriate place names, the final responsibility lies with the authors. Views expressed in the text are those of the authors and do not necessarily reflect the views of the publisher.
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Journal article(s) based on this preprint

05 Sep 2025
Measurement report: New particle formation events observed during the COALA-2020 campaign
Jhonathan Ramirez-Gamboa, Clare Paton-Walsh, Melita Keywood, Ruhi Humphries, Asher Mouat, Jennifer Kaiser, Malcom Possell, Jack Simmons, and Travis Naylor
Atmos. Chem. Phys., 25, 9937–9955, https://doi.org/10.5194/acp-25-9937-2025,https://doi.org/10.5194/acp-25-9937-2025, 2025
Short summary
Jhonathan Ramirez-Gamboa, Clare Paton-Walsh, Melita Keywood, Ruhi Humphries, Asher Mouat, Jennifer Kaiser, Malcom Possell, Jack Simmons, and Travis Naylor

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2062', Anonymous Referee #1, 13 Aug 2024
  • RC2: 'Comment on egusphere-2024-2062', Anonymous Referee #2, 04 Sep 2024
  • AC1: 'Response to referees egusphere-2024-2062', Jhonathan Ramirez Gamboa, 02 Dec 2024

Interactive discussion

Status: closed

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on egusphere-2024-2062', Anonymous Referee #1, 13 Aug 2024
  • RC2: 'Comment on egusphere-2024-2062', Anonymous Referee #2, 04 Sep 2024
  • AC1: 'Response to referees egusphere-2024-2062', Jhonathan Ramirez Gamboa, 02 Dec 2024

Peer review completion

AR: Author's response | RR: Referee report | ED: Editor decision | EF: Editorial file upload
AR by Jhonathan Ramirez Gamboa on behalf of the Authors (23 Dec 2024)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (29 Dec 2024) by Joachim Curtius
RR by Anonymous Referee #2 (22 Jan 2025)
RR by Anonymous Referee #1 (30 Jan 2025)
ED: Reconsider after major revisions (07 Feb 2025) by Joachim Curtius
AR by Jhonathan Ramirez Gamboa on behalf of the Authors (04 May 2025)  Author's response   Author's tracked changes   Manuscript 
ED: Referee Nomination & Report Request started (21 May 2025) by Joachim Curtius
RR by Anonymous Referee #2 (31 May 2025)
RR by Anonymous Referee #1 (12 Jun 2025)
ED: Publish subject to technical corrections (13 Jun 2025) by Joachim Curtius
AR by Jhonathan Ramirez Gamboa on behalf of the Authors (19 Jun 2025)  Author's response   Manuscript 

Journal article(s) based on this preprint

05 Sep 2025
Measurement report: New particle formation events observed during the COALA-2020 campaign
Jhonathan Ramirez-Gamboa, Clare Paton-Walsh, Melita Keywood, Ruhi Humphries, Asher Mouat, Jennifer Kaiser, Malcom Possell, Jack Simmons, and Travis Naylor
Atmos. Chem. Phys., 25, 9937–9955, https://doi.org/10.5194/acp-25-9937-2025,https://doi.org/10.5194/acp-25-9937-2025, 2025
Short summary
Jhonathan Ramirez-Gamboa, Clare Paton-Walsh, Melita Keywood, Ruhi Humphries, Asher Mouat, Jennifer Kaiser, Malcom Possell, Jack Simmons, and Travis Naylor
Jhonathan Ramirez-Gamboa, Clare Paton-Walsh, Melita Keywood, Ruhi Humphries, Asher Mouat, Jennifer Kaiser, Malcom Possell, Jack Simmons, and Travis Naylor

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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.

Short summary
Tiny air particles (aerosols) influence clouds, sunlight, and air chemistry. Our study examined how these particles form in a plant-rich region of Southeast Australia. We found frequent new particle formation (NPF) events, often linked to pollution plumes. VOCs from plants and other factors like humidity influence NPF and aerosol growth. Nighttime NPF requires further study. Overall, plant emissions play a key role in aerosol formation in this region.
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