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Title: Aerosol characteristics and particle production in the upper troposphere over the Amazon Basin

Airborne observations over the Amazon Basin showed high aerosol particle concentrations in the upper troposphere (UT) between 8 and 15 km altitude, with number densities (normalized to standard temperature and pressure) often exceeding those in the planetary boundary layer (PBL) by 1 or 2 orders of magnitude. The measurements were made during the German–Brazilian cooperative aircraft campaign ACRIDICON–CHUVA, where ACRIDICON stands for Aerosol, Cloud, Precipitation, and Radiation Interactions and Dynamics of Convective Cloud Systems and CHUVA is the acronym for Cloud Processes of the Main Precipitation Systems in Brazil: A Contribution to Cloud Resolving Modeling and to the GPM (global precipitation measurement), on the German High Altitude and Long Range Research Aircraft (HALO). The campaign took place in September–October 2014, with the objective of studying tropical deep convective clouds over the Amazon rainforest and their interactions with atmospheric trace gases, aerosol particles, and atmospheric radiation. Aerosol enhancements were observed consistently on all flights during which the UT was probed, using several aerosol metrics, including condensation nuclei (CN) and cloud condensation nuclei (CCN) number concentrations and chemical species mass concentrations. The UT particles differed sharply in their chemical composition and size distribution from those in the PBL, ruling out convective transportmore » of combustion-derived particles from the boundary layer (BL) as a source. The air in the immediate outflow of deep convective clouds was depleted of aerosol particles, whereas strongly enhanced number concentrations of small particles (< 90 nm diameter) were found in UT regions that had experienced outflow from deep convection in the preceding 5–72 h. We also found elevated concentrations of larger (> 90 nm) particles in the UT, which consisted mostly of organic matter and nitrate and were very effective CCN. Our findings suggest a conceptual model, where production of new aerosol particles takes place in the continental UT from biogenic volatile organic material brought up by deep convection and converted to condensable species in the UT. Subsequently, downward mixing and transport of upper tropospheric aerosol can be a source of particles to the PBL, where they increase in size by the condensation of biogenic volatile organic compound (BVOC) oxidation products. This may be an important source of aerosol particles for the Amazonian PBL, where aerosol nucleation and new particle formation have not been observed. We propose that this may have been the dominant process supplying secondary aerosol particles in the pristine atmosphere, making clouds the dominant control of both removal and production of atmospheric particles.« less
Authors:
ORCiD logo [1] ;  [2] ; ORCiD logo [3] ;  [4] ; ORCiD logo [5] ; ORCiD logo [5] ;  [4] ; ORCiD logo [6] ; ORCiD logo [2] ;  [7] ;  [8] ;  [9] ;  [8] ;  [4] ; ORCiD logo [4] ; ORCiD logo [10] ; ORCiD logo [2] ; ORCiD logo [11] ; ORCiD logo [12] ;  [13] more »; ORCiD logo [14] ;  [4] ;  [4] ; ORCiD logo [4] ;  [15] ; ORCiD logo [8] ;  [8] ;  [9] ; ORCiD logo [4] ; ORCiD logo [4] ;  [16] ;  [12] ; ORCiD logo [17] ;  [18] ; ORCiD logo [19] ; ORCiD logo [16] ; ORCiD logo [11] ; ORCiD logo [8] « less
  1. Max Planck Inst. for Chemistry, Mainz (Germany). Biogeochemistry, Multiphase Chemistry, and Particle Chemistry Dept.; Univ. of California, San Diego, CA (United States). Scripps Inst. of Oceanography
  2. Forschungszentrum Julich (Germany)
  3. Univ. of Sao Paulo (Brazil). Inst. of Astronomy, Geophysics and Atmospheric Sciences
  4. Max Planck Inst. for Chemistry, Mainz (Germany). Biogeochemistry, Multiphase Chemistry, and Particle Chemistry Dept.
  5. Univ. of Sao Paulo (Brazil). Inst. of Physics
  6. National Inst. for Space Research (INPE), Sao Jose dos Campos (Brazil); Univ. of Sao Paulo (Brazil). Inst. of Astronomy, Geophysics and Atmospheric Sciences
  7. Ludwig Maximilian Univ., Munich (Germany). Meteorological Inst.; Univ. of Vienna (Austria). Aerosol Physics and Environmental Physics
  8. German Aerospace Center (DLR), Wessling (Germany). Inst. of Atmospheric Physics (IPA)
  9. Karlsruhe Inst. of Technology (KIT) (Germany). Inst. for Meteorology and Climate Research
  10. Ludwig Maximilian Univ., Munich (Germany). Meteorological Inst.
  11. Leipzig Univ. (Germany). Leipzig Inst. for Meteorology
  12. National Inst. for Space Research (INPE), Sao Jose dos Campos (Brazil)
  13. Leibniz Inst. for Tropospheric Research, Leipzig (Germany)
  14. German Aerospace Center (DLR), Wessling (Germany). Inst. of Atmospheric Physics (IPA). Flight Experiments
  15. Hebrew Univ. of Jerusalem (Israel). Inst. of Earth Sciences
  16. German Aerospace Center (DLR), Wessling (Germany). Inst. of Atmospheric Physics (IPA); Univ. of Vienna (Austria). Aerosol Physics and Environmental Physics
  17. German Aerospace Center (DLR), Wessling (Germany). Inst. of Atmospheric Physics (IPA); Johannes Gutenberg Univ., Mainz (Germany). Inst. of Atmospheric Physics (IPA)
  18. Ludwig Maximilian Univ., Munich (Germany). Meteorological Inst.; German Aerospace Center (DLR), Wessling (Germany). Inst. of Atmospheric Physics (IPA)
  19. Max Planck Inst. for Chemistry, Mainz (Germany). Biogeochemistry, Multiphase Chemistry, and Particle Chemistry Dept.; Brookhaven National Lab. (BNL), Upton, NY (United States)
Publication Date:
Report Number(s):
BNL-203226-2018-JAAM
Journal ID: ISSN 1680-7324
Grant/Contract Number:
SC0012704; VO1504/4-1; SCHN1138/1-2; MI 583/4-1; JU 3059/1-1; WE 1900/22-1; WE 1900/24-1; WE 1900/36-1; 01LG1205E; W2/W3-60; VH-NG-606; 2014/08615-7; 2014/21189-7; 640458; 607905
Type:
Accepted Manuscript
Journal Name:
Atmospheric Chemistry and Physics (Online)
Additional Journal Information:
Journal Name: Atmospheric Chemistry and Physics (Online); Journal Volume: 18; Journal Issue: 2; Journal ID: ISSN 1680-7324
Publisher:
European Geosciences Union
Research Org:
Brookhaven National Laboratory (BNL), Upton, NY (United States)
Sponsoring Org:
USDOE; German Science Foundation (DFG); German Federal Ministry of Education and Research (BMBF); Helmholtz Association (Germany); Sao Paulo Research Foundation (FAPESP) (Brazil); European Research Council (ERC)
Country of Publication:
United States
Language:
English
Subject:
54 ENVIRONMENTAL SCIENCES
OSTI Identifier:
1425079