title: Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall.
abstract: The nucleation of atmospheric vapours is an important source of new aerosol particles that can subsequently grow to form cloud condensation nuclei in the atmosphere. Most field studies of atmospheric aerosols over continents are influenced by atmospheric vapours of anthropogenic origin (for example, ref. 2) and, in consequence, aerosol processes in pristine, terrestrial environments remain poorly understood. The Amazon rainforest is one of the few continental regions where aerosol particles and their precursors can be studied under near-natural conditions, but the origin of small aerosol particles that grow into cloud condensation nuclei in the Amazon boundary layer remains unclear. Here we present aircraft- and ground-based measurements under clean conditions during the wet season in the central Amazon basin. We find that high concentrations of small aerosol particles (with diameters of less than 50 nanometres) in the lower free troposphere are transported from the free troposphere into the boundary layer during precipitation events by strong convective downdrafts and weaker downward motions in the trailing stratiform region. This rapid vertical transport can help to maintain the population of particles in the pristine Amazon boundary layer, and may therefore influence cloud properties and climate under natural conditions.
authors: Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors: Jian
authors: J
authors: Wang
authors: Department of Applied Environmental Science and Analytical Chemistry, Stockholm University, Stockholm 10691, Sweden.
authors: Radovan
authors: R
authors: Krejci
authors: Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors: Scott
authors: S
authors: Giangrande
authors: Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors: Chongai
authors: C
authors: Kuang
authors: University of São Paulo, São Paulo 05508-900, Brazil.
authors: Henrique M J
authors: HM
authors: Barbosa
authors: University of São Paulo, São Paulo 05508-900, Brazil.
authors: Joel
authors: J
authors: Brito
authors: University of São Paulo, São Paulo 05508-900, Brazil.
authors: Samara
authors: S
authors: Carbone
authors: Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany.|School of Atmospheric Sciences, Nanjing University, and Collaborative Innovation Center for Climate Change, Jiangsu Province, 210023, Nanjing, China.
authors: Xuguang
authors: X
authors: Chi
authors: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors: Jennifer
authors: J
authors: Comstock
authors: Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors: Florian
authors: F
authors: Ditas
authors: Department of Biogeochemical Systems, Max Planck Institute for Biogeochemistry, 07745 Jena, Germany.
authors: Jost
authors: J
authors: Lavric
authors: Department of Physics, University of Helsinki, PO Box 64, FI-00014 Helsinki, Finland.
authors: Hanna E
authors: HE
authors: Manninen
authors: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors: Fan
authors: F
authors: Mei
authors: Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors: Daniel
authors: D
authors: Moran-Zuloaga
authors: Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors: Christopher
authors: C
authors: Pöhlker
authors: Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors: Mira L
authors: ML
authors: Pöhlker
authors: Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors: Jorge
authors: J
authors: Saturno
authors: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors: Beat
authors: B
authors: Schmid
authors: Amazonas State University, Amazonas 69050-020, Brazil.
authors: Rodrigo A F
authors: RA
authors: Souza
authors: Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors: Stephen R
authors: SR
authors: Springston
authors: Atmospheric Sciences and Global Change Division, Pacific Northwest National Laboratory, Richland, Washington 99352, USA.
authors: Jason M
authors: JM
authors: Tomlinson
authors: Environmental and Climate Sciences Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors: Tami
authors: T
authors: Toto
authors: Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany.
authors: David
authors: D
authors: Walter
authors: Department of Physics, University of Helsinki, PO Box 64, FI-00014 Helsinki, Finland.
authors: Daniela
authors: D
authors: Wimmer
authors: Department of Chemistry, University of California, Irvine, California 92697, USA.
authors: James N
authors: JN
authors: Smith
authors: Department of Physics, University of Helsinki, PO Box 64, FI-00014 Helsinki, Finland.
authors: Markku
authors: M
authors: Kulmala
authors: National Institute for Space Research, São José dos Campos, São Paulo 12227-010, Brazil.
authors: Luiz A T
authors: LA
authors: Machado
authors: University of São Paulo, São Paulo 05508-900, Brazil.
authors: Paulo
authors: P
authors: Artaxo
authors: Biogeochemistry and Multiphase Chemistry Departments, Max Planck Institute for Chemistry, 55128 Mainz, Germany.|Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92093, USA.
authors: Meinrat O
authors: MO
authors: Andreae
authors: Department of Physics, University of Helsinki, PO Box 64, FI-00014 Helsinki, Finland.
authors: Tuukka
authors: T
authors: Petäjä
authors: School of Engineering and Applied Sciences and Department of Earth and Planetary Sciences, Harvard University, Cambridge, Massachusetts 02138, USA.
authors: Scot T
authors: ST
authors: Martin
mesh_terms: D000336:Aerosols / Q000032:analysis* / Q000737:chemistry; D018533:Biomass; D001938:Brazil; D005390:Fires; D010316:Particle Size; D011891:Rain; D055549:Volatile Organic Compounds / Q000032:analysis / Q000737:chemistry
chemical_list: D000336:Aerosols; D055549:Volatile Organic Compounds