Mixing states of individual aerosol particles in spring Arctic troposphere during ASTAR 2000 campaign

Hara, Keiichiro

doi:10.1029/2002jd002513

Cited by 68 publications

(66 citation statements)

References 59 publications

(78 reference statements)

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“…The proportion of particles containing internally mixed soot is higher than that reported by Okada et al (2005) for Australia, Hara et al (2003) for the Arctic, and Hasegawa and Ohta (2002) for Japan and Alaska, even though most of our MC samples were less aged. Since our MC samples were collected close to their sources, generally within less than eight hours after emission and yet were coated when collected, we conclude that the rate of coating was rapid, consistent with the results of Doran et al (2007), Johnson et al (2005), and Baumgardner et al (2007).…”

Section: Om-s Coatings On Soot Particlescontrasting

confidence: 39%

Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City

2008

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Abstract. Soot particles, which are aggregated carbonaceous spherules with graphitic structures, are major aerosol constituents that result from burning of fossil fuel, biofuel, and biomass. Their properties commonly change through reaction with other particles or gases, resulting in complex internal mixtures. Using a transmission electron microscope (TEM) for both imaging and chemical analysis, we measured ∼8000 particles (25 samples) with aerodynamic diameters from 0.05 to 0.3 µm that were collected in March 2006 from aircraft over Mexico City (MC) and adjacent areas. Most particles are coated, consist of aggregates, or both. For example, almost all analyzed particles contain S and 70% also contain K, suggesting coagulation and condensation of sulfates and particles derived from biomass and biofuel burning. In the MC plumes, over half of all particles contained soot coated by organic matter and sulfates. The median value of the soot volume fraction in such coated particles is about 15%. In contrast to the assumptions used in many climate models, the soot particles did not become compact even when coated. Moreover, about 80% by volume of the particles consisting of organic matter with sulfate also contained soot, indicating the important role of soot in the formation of secondary aerosol particles. Coatings on soot particles can amplify their light absorption, and coagulation with sulfates changes their hygroscopic properties, resulting in shorter lifetimes. Through changes in their optical and hygroscopic properties, internally mixed soot particles have a greater effect on the regional climate of MC than uncoated soot particles.

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Section: Om-s Coatings On Soot Particlescontrasting

confidence: 39%

Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City

2008

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“…for estimating the aerosol mass mixing ratio). The main results of the entire airborne impactor measurements have already been discussed in detail in Hara et al (2002Hara et al ( , 2003. The findings for 23 and 26 March are as follows: the main components were sulfate, soot and sea salt particles; smaller components include a small number of mineral dust particles.…”

Section: Vertical Profile From Airborne Observationsmentioning

confidence: 75%

Arctic Study of Tropospheric Aerosol and Radiation (ASTAR) 2000: Arctic haze case study

Yamanouchi

Treffeisen

Herber

et al. 2005

Tellus B: Chemical and Physical Meteorology

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A strong haze event occurred between 21 and 25 March in which the optical depth from ground-based observation was 0.18, which was significantly greater than the background value of 0.06. Airborne measurements on 23 March during this haze event showed a high aerosol layer with an extinction coefficient of 0.03 km −1 or more up to 3 km and a scattering coefficient from 0.02 in the same altitude range. From the chemical analyses of airborne measurements, sulfate, soot and sea salt particles were dominant, and there was a high mixing ratio of external soot particles in some layers during the haze event, whereas internal mixing of soot in sulfate was noticeable in some layers for the background condition. We argue that the high aerosol loading is due to direct transport from anthropogenic source regions. In this paper we focus on the course of the haze event in detail through analyses of the airborne and ground-based results.

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“…The absorption efficiency for BC (7.3 m 2 g −1 ) is close to the recommended value of 7.5 m 2 g −1 from . In the atmosphere it is observed that BC is a combination of external and internal mixtures (Horvath, 1993;Hara et al, 2003;Wentzel et al, 2003;Mallet et al, 2004;Cheng et al, 2006). Further, it is well known that an internal mixture for BC enhances the absorption compared to an external mixture.…”

Section: Radiative Forcingmentioning

confidence: 94%

Black carbon in the atmosphere and snow, from pre-industrial times until present

et al. 2011

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Abstract. The distribution of black carbon (BC) in the atmosphere and the deposition of BC on snow surfaces since pre-industrial time until present are modelled with the Oslo CTM2 model. The model results are compared with observations including recent measurements of BC in snow in the Arctic. The global mean burden of BC from fossil fuel and biofuel sources increased during two periods. The first period, until 1920, is related to increases in emissions in North America and Europe, and the last period after 1970 are related mainly to increasing emissions in East Asia. Although the global burden of BC from fossil fuel and biofuel increases, in the Arctic the maximum atmospheric BC burden as well as in the snow was reached in 1960s, with a slight reduction thereafter. The global mean burden of BC from open biomass burning sources has not changed significantly since 1900. With current inventories of emissions from open biomass sources, the modelled burden of BC in snow and in the atmosphere north of 65 • N is small compared to the BC burden of fossil fuel and biofuel origin. From the concentration changes radiative forcing time series due to the direct aerosol effect as well as the snow-albedo effect is calculated for BC from fossil fuel and biofuel. The calculated radiative forcing in 2000 for the direct aerosol effect is 0.35 W m −2 and for the snow-albedo effect 0.016 W m −2 in this study. Due to a southward shift in the emissions there is an increase in the lifetime of BC as well as an increase in normalized radiative forcing, giving a change in forcing per unit of emissions of 26 % since 1950.

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Mixing states of individual aerosol particles in spring Arctic troposphere during ASTAR 2000 campaign

Cited by 68 publications

References 59 publications

Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City

Internally mixed soot, sulfates, and organic matter in aerosol particles from Mexico City

Arctic Study of Tropospheric Aerosol and Radiation (ASTAR) 2000: Arctic haze case study

Black carbon in the atmosphere and snow, from pre-industrial times until present

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