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.
Citation
@article{Wang2016,
author = {Wang, Jian and Krejci, Radovan and Giangrande, Scott and Kuang, Chongai and Barbosa, Henrique M. J. and Brito, Joel and Carbone, Samara and Chi, Xuguang and Comstock, Jennifer and Ditas, Florian and Lavric, Jost and Manninen, Hanna E. and Mei, Fan and Moran-Zuloaga, Daniel and Pöhlker, Christopher and Pöhlker, Mira L. and Saturno, Jorge and Schmid, Beat and Souza, Rodrigo A. F. and Springston, Stephen R. and Tomlinson, Jason M. and Toto, Tami and Walter, David and Wimmer, Daniela and Smith, James N. and Kulmala, Markku and Machado, Luiz A. T. and Artaxo, Paulo and Andreae, Meinrat O. and Petäjä, Tuukka and Martin, Scot T.},
doi = {10.1038/nature19819},
issn = {0028-0836},
journal = {Nature},
keywords = {Amazon,CLouds},
mendeley-tags = {Amazon,CLouds},
month = {oct},
pages = {1--17},
publisher = {Nature Publishing Group},
title = {Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall},
url = {http://dx.doi.org/10.1038/nature19819 http://www.nature.com/doifinder/10.1038/nature19819},
year = {2016}
}