Sensitivity of CCN spectra on chemical and physical properties of aerosol: A case study from the Amazon Basin

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Sensitivity of CCN spectra on chemical and physical properties of aerosol: A case study from the Amazon Basin. / Roberts, G C; Artaxo, P; Zhou, Jingchuan; Swietlicki, Erik; Andreae, M O.

In: Journal of Geophysical Research, Vol. 107, No. D20, 2002, p. 8070.

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T1 - Sensitivity of CCN spectra on chemical and physical properties of aerosol: A case study from the Amazon Basin

AU - Roberts, G C

AU - Artaxo, P

AU - Zhou, Jingchuan

AU - Swietlicki, Erik

AU - Andreae, M O

N1 - The information about affiliations in this record was updated in December 2015. The record was previously connected to the following departments: Nuclear Physics (Faculty of Technology) (011013007)

PY - 2002

Y1 - 2002

N2 - Organic material, about half of which is water soluble, constitutes nearly 80% of the wet-season aerosol mass in the Amazon Basin, while soluble inorganic salts (predominantly ammonium bisulfate) represent about 15%. A detailed analysis of number distributions and the size-dependent chemical composition of the aerosol indicates that, in principle, the sulfate fraction could account for most of the cloud condensation nuclei (CCN) activity. Uncertainty about the chemical speciation of the water-soluble organic component precludes a rigorous analysis of its contribution to nucleation activity. Within reasonable assumptions, we can, however, predict a similar contribution of the organic component to CCN activity as that from sulfate. Because of the nonlinear dependence of droplet nucleation behavior on solute amount, the nucleation activity cannot be attributed uniquely to the inorganic or organic fractions. The role of water-soluble organic compounds as surfactants, however, may be significant (especially in the case of biomass-burning aerosol) and more field measurements are needed to quantify their effects on the surface tension of ambient aerosols. The parametric dependence of the CCN spectra on the physical and chemical properties of the aerosol show that the number distribution, soluble content of the aerosol, and surface tension effects all play an important role in determining CCN spectra.

AB - Organic material, about half of which is water soluble, constitutes nearly 80% of the wet-season aerosol mass in the Amazon Basin, while soluble inorganic salts (predominantly ammonium bisulfate) represent about 15%. A detailed analysis of number distributions and the size-dependent chemical composition of the aerosol indicates that, in principle, the sulfate fraction could account for most of the cloud condensation nuclei (CCN) activity. Uncertainty about the chemical speciation of the water-soluble organic component precludes a rigorous analysis of its contribution to nucleation activity. Within reasonable assumptions, we can, however, predict a similar contribution of the organic component to CCN activity as that from sulfate. Because of the nonlinear dependence of droplet nucleation behavior on solute amount, the nucleation activity cannot be attributed uniquely to the inorganic or organic fractions. The role of water-soluble organic compounds as surfactants, however, may be significant (especially in the case of biomass-burning aerosol) and more field measurements are needed to quantify their effects on the surface tension of ambient aerosols. The parametric dependence of the CCN spectra on the physical and chemical properties of the aerosol show that the number distribution, soluble content of the aerosol, and surface tension effects all play an important role in determining CCN spectra.

U2 - 10.1029/2001JD000583

DO - 10.1029/2001JD000583

M3 - Article

VL - 107

SP - 8070

JO - Journal of Geophysical Research

JF - Journal of Geophysical Research

SN - 2156-2202

IS - D20

ER -