Optical, physical, and chemical properties of tar balls observed during the Yosemite Aerosol Characterization Study

Abstract

[1] The Yosemite Aerosol Characterization Study of summer 2002 (YACS) occurred during an active fire season in the western United States and provided an opportunity to investigate many unresolved issues related to the radiative effects of biomass burning aerosols. Single particle analysis was performed on field-collected aerosol samples using an array of electron microscopy techniques. Amorphous carbon spheres, or ''tar balls,'' were present in samples collected during episodes of high particle light scattering coefficients that occurred during the peak of a smoke/haze event. The highest concentrations of light-absorbing carbon from a dual-wavelength aethalometer (l = 370 and 880 nm) occurred during periods when the particles were predominantly tar balls, indicating they do absorb light in the UV and near-IR range of the solar spectrum. Closure experiments of mass concentrations and light scattering coefficients during periods dominated by tar balls did not require any distinct assumptions of organic carbon molecular weight correction factors, density, or refractive index compared to periods dominated by other types of organic carbon aerosols. Measurements of the hygroscopic behavior of tar balls using an environmental SEM indicate that tar balls do not exhibit deliquescence but do uptake some water at high ($83%) relative humidity. The ability of tar balls to efficiently scatter and absorb light and to absorb water has important implications for their role in regional haze and climate forcing.

Impact of Gobi desert dust on aerosol chemistry of Xi'an, inland China during spring 2009: differences in composition and size distribution between the urban ground surface and the mountain atmosphere

“…During the ageing process of biomass burning plume KCl can react with gaseous HNO 3 and H 2 SO4 and release HCl into the air (Ikegami et al, 2001;Li et al, 2003;Posfai et al, 2003). The gaseous HCl further transforms into aerosol phase by reaction with coarse particles (Hand et al, 2005;Tobo et al, 2010). Therefore, a bimodal pattern of Cl − was obtained in the urban region (Fig.…”

Ns-Soot: A Material-Based Term for Strongly Light-Absorbing Carbonaceous Particles

“…They provide enough information for the unambiguous identification of ns-soot, which, in turn, is useful for assessing the relative concentration and mixing properties of this important particle type. In contrast, tar balls, which are also spherical, lack distinctive diffraction features and the wavy, graphene-like layers that are characteristic of ns-soot (P osfai et al 2004;Hand et al 2005;Adachi and Buseck 2011). Other organic particles, either of primary or secondary origin, also lack structures that are readily identifiable in TEM measurements (Chen et al 2006;Adachi and Buseck 2008).…”

Individual Particle Analysis of Atmospheric Aerosols at Nam Co, Tibetan Plateau

“…Tar ball is produced from biomass and biofuel burning. The further investigation shows tar ball can scatter and absorb light efficiently and then may play an important role in climate forcing (Hand et al, 2005).…”