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| Titel |
Cloud Condensation Nuclei and Chemical Composition of size-resolved particles in a Brazilian megacity: Effect of NPF event, biomass burning and sea salt from remote regions on the CCN properties |
| VerfasserIn |
Carlos Souto-Oliveira, Maria de Fatima Andrade, Prashant Kumar, Fabio Lopes, Marly Babinski, Eduado Landulfo, Angel Vara-Vela |
| Konferenz |
EGU General Assembly 2016
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 18 (2016) |
| Datensatznummer |
250130474
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| Publikation (Nr.) |
 EGU/EGU2016-10733.pdf |
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| Zusammenfassung |
| Atmospheric aerosol particles are an important source of cloud condensation nuclei (CCN).
Their microphysics and chemical composition can directly affect development of clouds and
precipitation process1,2. Only a few studies in Latin American have reported the impact of
urban aerosol on the formation of CCN and their contribution to global climate change3. In
this study, we simultaneously measured size distributed particle number concentration (PNC),
CCN, black carbon (BC) and elemental concentrations (EC) in aerosol samples from
São Paulo city. The PNC was measured by DMPS (model 3936) operated with a
DMA (model 3080) and CPC (TSI, model 3010). The CCN was measuredby a
single-column continuous-flow stream-wise thermal gradient CCN chamber (DMT
CCNC-100). The BC and EC were determined in polycarbonate filter collected by
Cascade Impactor (MOUDI-MSP), using a smoke stain reflectometer and an ED-XRF
(EDX 700; Shimadzu), respectively. During the study period, which was August
to September 2014, four events of new particle formation (NPF), characterizing
secondary process of aerosol formation were noted. The total PNC varied between 1106
and 29168 cm−3, while CCN presented concentrations of 206 to 12761 cm−3for
SS=1.0%. The PNC showed different concentrations during diurnal and nocturnal
periods with average of 16392±7811 cm−3 and 6874±3444cm−3, respectively. The
activated ratio (CCN/CN) presented diurnal and nocturnal values of 0.19±0.10 and
0.41±0.18, while apparent activation diameter (Dact,a) was estimated to be 110±29 and
71±28 nm (SS=0.6%), respectively. Combining EC and BC results with air mass
trajectory analysis (Lidar aerosol profiles and Hysplit air trajectories), apportionment
events were identified for sea salt and biomass burning from coastal and continental
regions, respectively. The nocturnal AR and Dact,apresented values of 0.46±0.11 and
49±15 nm (SS=0.6%) for sea salt events as opposed to 0.33±0.14 and 64±30 nm
(SS=0.6%) during biomass burning events. Although statistically not robust, it
was observed diurnal and nocturnal tendencies for CCN properties (AR, Dact,a),
which were accompanied by small variability for sea salt and biomass burning
events.
References
[1] Andreae et al. (2004). Science, 303, 1337–1342.
[2] Andreae, M. O., and Rosenfeld, D. (2008). Earth-Science Reviews, 89, 13–41.
[3] Almeida et al. Atmospheric Chemistry and Physics, 14, 7559–7572. |
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