Help Privacy Policy Disclaimer
  Advanced SearchBrowse


  Occurrence and growth of sub-50 nm aerosol particles in the Amazonian boundary layer

Franco, M. A., Ditas, F., Kremper, L. A., Machado, L. A. T., Andreae, M. O., Araújo, A., et al. (2022). Occurrence and growth of sub-50 nm aerosol particles in the Amazonian boundary layer. Atmospheric Chemistry and Physics, 22(5), 3469-3492. doi:10.5194/acp-22-3469-2022.

Item is


show Files




Franco, Marco A., Author
Ditas, Florian1, Author           
Kremper, Leslie Ann1, Author           
Machado, Luiz A. T., Author
Andreae, Meinrat O.1, Author           
Araújo, Alessandro, Author
Barbosa, Henrique M. J., Author
de Brito, Joel F., Author
Carbone, Samara, Author
Holanda, Bruna A.1, Author           
Morais, Fernando G., Author
Nascimento, Janaína P., Author
Pöhlker, Mira L.1, Author           
Rizzo, Luciana V., Author
Sá, Marta, Author
Saturno, Jorge, Author
Walter, David1, Author           
Wolff, Stefan1, Author           
Pöschl, Ulrich1, Author           
Artaxo, Paulo, Author
Pöhlker, Christopher1, Author            more..
1Multiphase Chemistry, Max Planck Institute for Chemistry, Max Planck Society, ou_1826290              


Free keywords: -
 Abstract: New particle formation (NPF), referring to the nucleation of molecular clusters and their subsequent growth into the cloud condensation nuclei (CCN) size range, is a globally significant and climate-relevant source of atmospheric aerosols. Classical NPF exhibiting continuous growth from a few nanometers to the Aitken mode around 60–70 nm is widely observed in the planetary boundary layer (PBL) around the world but not in central Amazonia. Here, classical NPF events are rarely observed within the PBL, but instead, NPF begins in the upper troposphere (UT), followed by downdraft injection of sub-50 nm (CN<50) particles into the PBL and their subsequent growth. Central aspects of our understanding of these processes in the Amazon have remained enigmatic, however. Based on more than 6 years of aerosol and meteorological data from the Amazon Tall Tower Observatory (ATTO; February 2014 to September 2020), we analyzed the diurnal and seasonal patterns as well as meteorological conditions during 254 of such Amazonian growth events on 217 event days, which show a sudden occurrence of particles between 10 and 50 nm in the PBL, followed by their growth to CCN sizes. The occurrence of events was significantly higher during the wet season, with 88 % of all events from January to June, than during the dry season, with 12 % from July to December, probably due to differences in the condensation sink (CS), atmospheric aerosol load, and meteorological conditions. Across all events, a median growth rate (GR) of 5.2 nm h−1 and a median CS of 1.1 × 10−3 s−1 were observed. The growth events were more frequent during the daytime (74 %) and showed higher GR (5.9 nm h−1) compared to nighttime events (4.0 nm h−1), emphasizing the role of photochemistry and PBL evolution in particle growth. About 70 % of the events showed a negative anomaly of the equivalent potential temperature () – as a marker for downdrafts – and a low satellite brightness temperature (Tir) – as a marker for deep convective clouds – in good agreement with particle injection from the UT in the course of strong convective activity. About 30 % of the events, however, occurred in the absence of deep convection, partly under clear-sky conditions, and with a positive anomaly. Therefore, these events do not appear to be related to downdraft transport and suggest the existence of other currently unknown sources of sub-50 nm particles.


Language(s): eng - English
 Dates: 2022-03-16
 Publication Status: Published online
 Pages: 36
 Publishing info: -
 Table of Contents: -
 Rev. Type: No review
 Identifiers: DOI: 10.5194/acp-22-3469-2022
 Degree: -



Legal Case


Project information


Source 1

Title: Atmospheric Chemistry and Physics
  Abbreviation : ACP
Source Genre: Journal
Publ. Info: -
Pages: - Volume / Issue: 22 (5) Sequence Number: - Start / End Page: 3469 - 3492 Identifier: ISSN: 1680-7316
CoNE: https://pure.mpg.de/cone/journals/resource/111030403014016