Characterisation of aerosol properties and radiative forcing at an anthropogenically perturbed continental site

S. Koloutsou-Vakakis, C. M. Carrico, Z. Li, M. J. Rood, J. A. Ogren

Research output: Contribution to journalArticlepeer-review


Measurements of optical, chemical and physical properties of ambient aerosol particles were obtained at a continental anthropogenically pertubed environment. For aerosol sampled at the site from January to December 1995, the mean gravimetric mass concentration for particles with diameter d(p) ≤ 1μm on 24-hr filter samples was 11.0 ± 7.6 μg/m3. Ion chromatographic (IC) analysis chemically identified 50 ± 15% of the total gravimetric mass for fine particles (d(p) ≤ 1 μm). Most of the IC identified material (88 ± 14%) consisted of NH4+ and SO42-. Thermal optical reflectance (TOR) analysis of small number of samples showed that the material not identified with IC consisted of elemental and organic carbon. To examine the implications of the measurements and effect of their variation, the mean annual direct radiative forcing (ΔF(R)) due to aerosol particles at the site was estimated by a simple model using as input measured total light scattering coefficients, hemispheric backscatter ratio and hygroscopic growth factor. For a mean annual height of the mixed layer at 800 m, an assumed single scattering albedo (ω) value of 0.85 and wavelength 550 nm,ΔF(R) as function of relative humidity (RH) ranged between -0.51±0.47 (RH = 40%) and -0.63 ±0.58 (RH = 80%) W/m2. Sensitivity tests pointed to the importance of accurate quantification of ω.

Original languageEnglish (US)
Pages (from-to)541-546
Number of pages6
JournalPhysics and Chemistry of the Earth, Part C: Solar, Terrestrial and Planetary Science
Issue number5
StatePublished - 1999

ASJC Scopus subject areas

  • General Earth and Planetary Sciences


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