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Title: Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall

Abstract

A necessary prerequisite of cloud formation, aerosol particles represent one of the largest uncertainties in computer simulations of climate change1,2, in part because of a poor understanding of processes under natural conditions3,4. The Amazon rainforest is one of the few continental regions where aerosol particles and their precursors can be studied under near-natural conditions5-7. Cloud condensation nuclei (CCN) in clean Amazonia are mostly produced by the growth of smaller particles in the boundary layer8-10, whereas these smaller particles themselves 31 appear to be produced elsewhere5,11. Key questions are in what part of the atmosphere they might 32 be produced and what could be the transport processes that deliver them to the boundary layer, where they grow into CCN. Here, using recent aircraft measurements above central Amazonia, we show high concentrations of small particles in the lower free troposphere. The particle size spectrum shifts towards larger sizes with decreasing altitude, implying particle growth as air descends from the free troposphere towards Earth's surface. Complementary measurements at ground sites show that free tropospheric air having high concentrations of small particles (diameters of less than 50 nm) is transported into the boundary layer during precipitation events, both by strong convective downdrafts and bymore » weaker downward motions in the trailing stratiform region. This vertical transport helps maintain the population of small particles and ultimately CCN in the boundary layer, thereby playing an important role in controlling the climate state under natural conditions. In contrast, this mechanism becomes masked under polluted conditions, which sometimes prevail at times in Amazonia as well as over other tropical continental regions5,12.« less

Authors:
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Publication Date:
Research Org.:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1339873
Report Number(s):
PNNL-SA-117828
Journal ID: ISSN 0028-0836; KP1704010
DOE Contract Number:  
AC05-76RL01830
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature (London); Journal Volume: 539; Journal Issue: 7629
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES

Citation Formats

Wang, Jian, Krejci, Radovan, Giangrande, 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, Pöhlker, Christopher, Pöhlker, 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., Petäjä, Tuukka, and Martin, Scot T.. Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall. United States: N. p., 2016. Web. doi:10.1038/nature19819.
Wang, Jian, Krejci, Radovan, Giangrande, 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, Pöhlker, Christopher, Pöhlker, 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., Petäjä, Tuukka, & Martin, Scot T.. Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall. United States. doi:10.1038/nature19819.
Wang, Jian, Krejci, Radovan, Giangrande, 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, Pöhlker, Christopher, Pöhlker, 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., Petäjä, Tuukka, and Martin, Scot T.. Mon . "Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall". United States. doi:10.1038/nature19819.
@article{osti_1339873,
title = {Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall},
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.},
abstractNote = {A necessary prerequisite of cloud formation, aerosol particles represent one of the largest uncertainties in computer simulations of climate change1,2, in part because of a poor understanding of processes under natural conditions3,4. The Amazon rainforest is one of the few continental regions where aerosol particles and their precursors can be studied under near-natural conditions5-7. Cloud condensation nuclei (CCN) in clean Amazonia are mostly produced by the growth of smaller particles in the boundary layer8-10, whereas these smaller particles themselves 31 appear to be produced elsewhere5,11. Key questions are in what part of the atmosphere they might 32 be produced and what could be the transport processes that deliver them to the boundary layer, where they grow into CCN. Here, using recent aircraft measurements above central Amazonia, we show high concentrations of small particles in the lower free troposphere. The particle size spectrum shifts towards larger sizes with decreasing altitude, implying particle growth as air descends from the free troposphere towards Earth's surface. Complementary measurements at ground sites show that free tropospheric air having high concentrations of small particles (diameters of less than 50 nm) is transported into the boundary layer during precipitation events, both by strong convective downdrafts and by weaker downward motions in the trailing stratiform region. This vertical transport helps maintain the population of small particles and ultimately CCN in the boundary layer, thereby playing an important role in controlling the climate state under natural conditions. In contrast, this mechanism becomes masked under polluted conditions, which sometimes prevail at times in Amazonia as well as over other tropical continental regions5,12.},
doi = {10.1038/nature19819},
journal = {Nature (London)},
number = 7629,
volume = 539,
place = {United States},
year = {Mon Oct 24 00:00:00 EDT 2016},
month = {Mon Oct 24 00:00:00 EDT 2016}
}