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Optical and physical properties of aerosols in the boundary layer and free troposphere over the Amazon Basin during the biomass burning season

Chand, D. ; Guyon, P. ; Artaxo, P. ; Schmid, O. ; Frank, G. P. LU orcid ; Rizzo, L. V. ; Mayol-Bracero, O. L. ; Gatti, L. V. and Andreae, M. O. (2006) In Atmospheric Chemistry and Physics 6(10). p.2911-2925
Abstract

As part of the Large Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke, Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) campaign, detailed surface and airborne aerosol measurements were performed over the Amazon Basin during the dry to wet season from 16 September to 14 November 2002. Optical and physical properties of aerosols at the surface, and in the boundary layer (BL) and free troposphere (FT) during the dry season are discussed in this article. Carbon monoxide (CO) is used as a tracer for biomass burning emissions. At the surface, good correlation among the light scattering coefficient (σs at 545 nm), PM2.5, and CO indicates that biomass burning is the main source of aerosols. Accumulation of haze during... (More)

As part of the Large Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke, Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) campaign, detailed surface and airborne aerosol measurements were performed over the Amazon Basin during the dry to wet season from 16 September to 14 November 2002. Optical and physical properties of aerosols at the surface, and in the boundary layer (BL) and free troposphere (FT) during the dry season are discussed in this article. Carbon monoxide (CO) is used as a tracer for biomass burning emissions. At the surface, good correlation among the light scattering coefficient (σs at 545 nm), PM2.5, and CO indicates that biomass burning is the main source of aerosols. Accumulation of haze during some of the large-scale biomass burning events led to high PM2.5 (225 μgm-3), σs, (1435 Mm-1), aerosol optical depth at 500 nm (3.0), and CO (3000ppb). A few rainy episodes reduced the PM2.5, number concentration (CN) and CO concentration by two orders of magnitude. The correlation analysis between σs and aerosol optical thickness shows that most of the optically active aerosols are confined to a layer with a scale height of 1617m during the burning season. This is confirmed by aircraft profiles. The average mass scattering and absorption efficiencies (545 nm) for small particles (diameter Dp < 1.5 μm) at surface level are found to be 5.0 and 0.33 m2 g-1, respectively, when relating the aerosol optical properties to PM2.5 aerosols. The observed mean single scattering albedo (ω>0 at 545 nm) for submicron aerosols at the surface is 0.92±0.02. The light scattering by particles (Δσs/ΔCN) increase 2-10 times from the surface to the FT, most probably due to the combined affects of coagulation and condensation.

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author
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publishing date
type
Contribution to journal
publication status
published
in
Atmospheric Chemistry and Physics
volume
6
issue
10
pages
15 pages
publisher
Copernicus GmbH
external identifiers
  • scopus:33746237496
ISSN
1680-7316
DOI
10.5194/acp-6-2911-2006
language
English
LU publication?
no
id
32d1187c-5fe8-4a5d-83d1-7b75cd15a45f
date added to LUP
2020-11-09 15:04:11
date last changed
2022-05-04 21:34:40
@article{32d1187c-5fe8-4a5d-83d1-7b75cd15a45f,
  abstract     = {{<p>As part of the Large Scale Biosphere-Atmosphere Experiment in Amazonia - Smoke, Aerosols, Clouds, Rainfall and Climate (LBA-SMOCC) campaign, detailed surface and airborne aerosol measurements were performed over the Amazon Basin during the dry to wet season from 16 September to 14 November 2002. Optical and physical properties of aerosols at the surface, and in the boundary layer (BL) and free troposphere (FT) during the dry season are discussed in this article. Carbon monoxide (CO) is used as a tracer for biomass burning emissions. At the surface, good correlation among the light scattering coefficient (σ<sub>s</sub> at 545 nm), PM2.5, and CO indicates that biomass burning is the main source of aerosols. Accumulation of haze during some of the large-scale biomass burning events led to high PM2.5 (225 μgm<sup>-3</sup>), σ<sub>s</sub>, (1435 Mm<sup>-1</sup>), aerosol optical depth at 500 nm (3.0), and CO (3000ppb). A few rainy episodes reduced the PM2.5, number concentration (CN) and CO concentration by two orders of magnitude. The correlation analysis between σ<sub>s</sub> and aerosol optical thickness shows that most of the optically active aerosols are confined to a layer with a scale height of 1617m during the burning season. This is confirmed by aircraft profiles. The average mass scattering and absorption efficiencies (545 nm) for small particles (diameter D<sub>p</sub> &lt; 1.5 μm) at surface level are found to be 5.0 and 0.33 m<sup>2</sup> g<sup>-1</sup>, respectively, when relating the aerosol optical properties to PM2.5 aerosols. The observed mean single scattering albedo (ω&gt;0 at 545 nm) for submicron aerosols at the surface is 0.92±0.02. The light scattering by particles (Δσ<sub>s</sub>/ΔCN) increase 2-10 times from the surface to the FT, most probably due to the combined affects of coagulation and condensation.</p>}},
  author       = {{Chand, D. and Guyon, P. and Artaxo, P. and Schmid, O. and Frank, G. P. and Rizzo, L. V. and Mayol-Bracero, O. L. and Gatti, L. V. and Andreae, M. O.}},
  issn         = {{1680-7316}},
  language     = {{eng}},
  number       = {{10}},
  pages        = {{2911--2925}},
  publisher    = {{Copernicus GmbH}},
  series       = {{Atmospheric Chemistry and Physics}},
  title        = {{Optical and physical properties of aerosols in the boundary layer and free troposphere over the Amazon Basin during the biomass burning season}},
  url          = {{http://dx.doi.org/10.5194/acp-6-2911-2006}},
  doi          = {{10.5194/acp-6-2911-2006}},
  volume       = {{6}},
  year         = {{2006}},
}