Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall

Author(s):Show less -

Wang, Jian ; Krejci, Radovan ; Giangrandel, Scott ; Kuang, Chongai ; Barbosa, Henrique M. J. ; Brito, Joel ; Carbone, Samara ; Chi, Xuguang ; Comstock, Jennifer ; Ditas, Florian ; Lavric, Jost ; Manninen, Hanna E. ; Mei, Fan ; Moran-Zuloaga, Daniel ; Poehlker, Christopher ; Poehlker, Mira L. ; Saturno, Jorge ; Schmid, Beat ; Souza, Rodrigo A. F. ; Springston, Stephen R. ; Tomlinson, Jason M. ; Toto, Tami ; Walter, David ; Wimmer, Daniela ; Smith, James N. ; Kulmala, Markku ; Machado, Luiz A. T. ; Artaxo, Paulo ; Andreae, Meinrat O. ; Petaja, Tuukka ; Martin, Scot T.

• Document type: Journal article
• Source: Nature; v. 539, n. 7629, p. 416-419, NOV 17 2016.
• Web of Science Citations: 29

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(1). 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(3-5), but the origin of small aerosol particles that grow into cloud condensation nuclei in the Amazon boundary layer remains unclear(6-8). 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. (AU)

• FAPESP's process: 13/05014-0 - GoAmazon: interactions of the urban plume of Manaus with biogenic forest emissions in Amazonia
• Grantee: Paulo Eduardo Artaxo Netto
• Support type: Research Program on Global Climate Change - Thematic Grants
• FAPESP's process: 09/15235-8 - Cloud processes of the main precipitation systems in Brazil: a contribution to cloud resolving modeling and to the GPM (Global Precipitation Measurement)
• Grantee: Luiz Augusto Toledo Machado
• Support type: Research Projects - Thematic Grants
• FAPESP's process: 13/50510-5 - Brazil-USA collaborative research: modifications by anthropogenic pollution of the natural atmospheric chemistry and particle microphysics of the tropical rain forest during GoAmazon intensive operating periods
• Grantee: Henrique de Melo Jorge Barbosa
• Support type: Research Program on Global Climate Change - Regular Grants