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| Titel |
CCN activation and efficiency of nucleation and impaction removal process of biomass burning aerosols in Brazil: preliminary results. |
| VerfasserIn |
Madeleine Sánchez Gácita, Karla M. Longo, Saulo R. Freitas, Scot T. Martin |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250108609
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| Publikation (Nr.) |
 EGU/EGU2015-8373.pdf |
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| Zusammenfassung |
| The biomass burning activity constitutes an important source of aerosols and trace
gases to the atmosphere globally. In South America, during the dry season, aerosols
prevenient from biomass burning are typically transported to long distances from
its sources before being removed though contributing significantly to the aerosol
budget on a continental scale. The uncertainties in the magnitude of the impacts on
the hydrological cycle, the radiation budget and the biogeochemical cycles on a
continental scale are still noteworthy. The still unknowns on the efficiency of biomass
burning aerosol to act as cloud condensation nuclei (CCN) and the effectiveness
of the nucleation and impaction scavenging mechanisms in removing them from
the atmosphere contribute to such uncertainties. In the present work, the explicit
modelling of the early stages of cloud development using a parcel model for the typical
conditions of the dry season and dry-to-wet transition periods in Amazonia allowed an
estimation of the efficiency of nucleation scavenging process and the ability of
South American biomass burning aerosol to act as CCN. Additionally, the impaction
scavenging was simulated for the same aerosol population following a method
based on the widely used concept of the efficiency of collision between a raindrop
and an aerosol particle. DMPS and H-TDMA data available in the literature for
biomass burning aerosol population in the region indicated the presence of a nearly
hydrophobic fraction (on average, with specific hygroscopic parameter κ=0.04,
and relative abundance of 73 %) and nearly hygroscopic fraction (κ=0.13, 27 %),
externally mixed. The hygroscopic parameters and relative abundances of each
hygroscopic group, as well as the weighted average specific hygroscopic parameter for
the entire population κ=0.06, were used in calculations of aerosol activation and
population mass and number concentration scavenged by nucleation. Results from both
groups of simulations are presented and discussed. This work provides an insight
on the importance of the inclusion of these processes in regional/global models.
The authors thank the Sao Paulo Research Foundation FAPESP for supporting
this work through the projects DR 2012/09934-3 and BEPE-DR 2013/02101-9. |
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