|
Read Full Article (file size: 651520 bytes) Cited by
JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 113,
D12213,
doi:10.1029/2007JD009393,
2008
Chemically segregated optical and microphysical properties of ambient aerosols measured in a single-particle mass spectrometer
Ryan C. Moffet
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
Xueying Qin
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
Thomas Rebotier
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
Hiroshi Furutani
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, California, USA
Kimberly A. Prather
Department of Chemistry and Biochemistry, Scripps Institution of Oceanography, University of California, San Diego, La Jolla,
California, USA
Abstract
This paper describes results from the first direct measurements of the size-resolved optical properties as a function of chemical
mixing states for atmospheric particle types sampled in Mexico City and Riverside, California. The coupled size, chemistry,
and optical measurements were used to derive refractive indices and effective densities for chemically distinct particle mixing
states. On the basis of the measured dependence of scattering intensity as a function of relative humidity and size, the Riverside
particles contained detectable amounts of liquid water, whereas the Mexico City particles were relatively dry. Aerosol particles
in Mexico City were observed to exhibit a wide range of densities (1.1–3.4 g/cm3), suggesting a dynamic, externally mixed aerosol population. Daily variations were observed as the particles in Mexico City
underwent photochemical aging processes leading to a diurnal variation in particle morphology. In contrast, the optical properties
of the Riverside aerosol, sampled during the fall season, were strongly impacted by the condensation of water and ammonium
nitrate during periods of intense pollution buildup, resulting in microphysical properties that were similar across mixing
states for a specific relative humidity.
Received 16
September
2007;
accepted 13
March
2008;
published 27
June
2008.
Keywords: aerosol;
refractive index;
density.
Index Terms: 0305 Atmospheric Composition and Structure: Aerosols and particles (0345, 4801, 4906); 0365 Atmospheric Composition and Structure: Troposphere: composition and chemistry; 0360 Atmospheric Composition and Structure: Radiation: transmission and scattering; 0629 Electromagnetics: Inverse scattering; 0394 Atmospheric Composition and Structure: Instruments and techniques.
Read Full Article (file size: 651520 bytes) Cited by
Citation: Moffet, R. C., X. Qin, T. Rebotier, H. Furutani, and K. A. Prather
(2008),
Chemically segregated optical and microphysical properties of ambient aerosols measured in a single-particle mass spectrometer,
J. Geophys. Res.,
113,
D12213,
doi:10.1029/2007JD009393.
Copyright 2008 by the American Geophysical Union.
|