Cloud condensation nuclei activity of fresh primary and aged biomass burning aerosol

Engelhart, G. J.; Hennigan, Christopher J.; Miracolo, Marissa A.; Robinson, Allen L.; Pandis, Spyros Ν.

doi:10.5194/acp-12-7285-2012

Cited by 121 publications

(155 citation statements)

References 36 publications

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“…Results for D 0 = 110 nm are similar, except for a vanishing contribution of the more-hygroscopic background mode and a broader and slightly more hygroscopic fresh emissions mode (peaking between GF ≈ 1.15-1.3). These observations are consistent with variable, but moderate hygroscopicity of fresh biomass burning emissions from different sources (e.g., Petters et al, 2009;Engelhart et al, 2012;Martin et al, 2013). Condensation of secondary organic and inorganic matter on the primary particles in the concentrated biomass burning plume may also contribute to slightly larger GFs at smaller dry sizes.…”

Section: Aerosol Hygroscopicitysupporting

confidence: 75%

Black carbon physical properties and mixing state in the European megacity Paris

et al. 2013

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Aerosol hygroscopicity and refractory black carbon (rBC) properties were characterised during wintertime at a suburban site in Paris, one of the biggest European cities. Hygroscopic growth factor (GF) frequency distributions, characterised by distinct modes of more-hygroscopic background aerosol and non- or slightly hygroscopic aerosol of local (or regional) origin, revealed an increase of the relative contribution of the local sources compared to the background aerosol with decreasing particle size. BC-containing particles in Paris were mainly originating from fresh traffic emissions, whereas biomass burning only gave a minor contribution. The mass size distribution of the rBC cores peaked on average at an rBC core mass equivalent diameter of D_MEV ~ 150 nm. The BC-containing particles were moderately coated (coating thickness Δ_coat ~ 33 nm on average for rBC cores with D_MEV = 180–280 nm) and an average mass absorption coefficient (MAC) of ~ 8.6 m² g⁻¹ at the wavelength λ = 880 nm was observed.

Different time periods were selected to investigate the properties of BC-containing particles as a function of source and air mass type. The traffic emissions were found to be non-hygroscopic (GF ≈ 1.0), and essentially all particles with a dry mobility diameter (D₀) larger than D₀ = 110 nm contained an rBC core. rBC from traffic emissions was further observed to be uncoated within experimental uncertainty (Δ_coat ~ 2 nm ± 10 nm), to have the smallest BC core sizes (maximum of the rBC core mass size distribution at D_MEV ~ 100 nm) and to have the smallest MAC (~ 7.3 m²g⁻¹ at λ = 880 nm).

The biomass burning aerosol was slightly more hygroscopic than the traffic emissions (with a distinct slightly-hygroscopic mode peaking at GF ≈ 1.1–1.2). Furthermore, only a minor fraction (≤ 10%) of the slightly-hygroscopic particles with 1.1 ≤ GF ≤ 1.2 (and D₀ = 265 nm) contained a detectable rBC core. The BC-containing particles from biomass burning were found to have a medium coating thickness as well as slightly larger mean rBC core sizes and MAC values compared to traffic emissions.

The aerosol observed under the influence of aged air masses and air masses from Eastern Continental Europe was dominated by a~more-hygroscopic mode peaking at GF ≈ 1.6. Most particles (95%), in the more-hygroscopic mode at D₀ = 265 nm, did not contain a detectable rBC core. A significant fraction of the BC-containing particles had a substantial coating with non-refractory aerosol components. MAC values of ~ 8.8 m²g⁻¹ and ~ 8.3 m²g⁻¹ at λ = 880 nm and mass mean rBC core diameters of 150 nm and 200 nm were observed for the aged and continental air mass types, respectively. The reason for the larger rBC core sizes compared to the fresh emissions – transp...

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Section: Aerosol Hygroscopicitysupporting

confidence: 75%

Black carbon physical properties and mixing state in the European megacity Paris

et al. 2013

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“…Accumulation type aerosol was connected to long-range transport from the Sahara and Sahel region, where either mineral dust from the desert and/or biomass-burning particles from the Sahel were involved in raising the particle number concentrations in the accumulation mode. Although particles from both biomass burning and mineral dust are sometimes assumed to be of rather insoluble nature, they have been shown to contribute to CCN (Engelhart et al, 2012;Twohy et al, 2009;Karydis et al, 2011), and an increase in N CCN due to their presence was also observed in the present study.…”

Section: Discussionsupporting

confidence: 62%

Aerosol arriving on the Caribbean island of Barbados: physical properties and origin

et al. 2016

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Abstract. The marine aerosol arriving at Barbados (Ragged Point) was characterized during two 3-week long measurement periods in November 2010 and April 2011, in the context of the measurement campaign CARRIBA (Cloud, Aerosol, Radiation and tuRbulence in the trade wInd regime over BArbados). Through a comparison between groundbased and airborne measurements it was shown that the former are representative of the marine boundary layer at least up to cloud base. In general, total particle number concentrations (N total ) ranged from as low as 100 up to 800 cm −3 , while number concentrations for cloud condensation nuclei (N CCN ) at a supersaturation of 0.26 % ranged from some 10 to 600 cm −3 . N total and N CCN depended on the air mass origin. Three distinct types of air masses were found. One type showed elevated values for both N total and N CCN and could be attributed to long-range transport from Africa, by which biomass burning particles from the Sahel region and/or mineral dust particles from the Sahara were advected. The second and third type both had values for N CCN below 200 cm −3 and a clear minimum in the particle number size distribution (NSD) around 70 to 80 nm (Hoppel minimum). While for one of these two types the accumulation mode was dominating (albeit less so than for air masses advected from Africa), the Aitken mode dominated the other and contributed more than 50 % of all particles. These Aitken mode particles likely were formed by new particle formation no more than 3 days prior to the measurements. Hygroscopicity of particles in the CCN size range was determined from CCN measurements to be κ = 0.66 on average, which suggests that these particles contain mainly sulfate and do not show a strong influence from organic material, which might generally be the case for the months during which measurements were made. The average κ could be used to derive N CCN from measured number size distributions, showing that this is a valid approach to obtain N CCN . Although the total particulate mass sampled on filters was found to be dominated by Na + and Cl − , this was found to be contributed by a small number of large particles (> 500 nm, mostly even in the super-micron size range). Based on a three-modal fit, a sea spray mode observed in the NSDs was found to contribute 90 % to the total particulate mass but only 4 to 10 % to N total and up to 15 % to N CCN . This is in accordance with finding no correlation between N total and wind speed.

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“…Regarding the indirect effect, particles that are larger in diameter and more hygroscopic are more likely to act as CCN (Petters and Kreidenweis, 2007). Typically, particles larger than 30-100 nm act as CCN depending on conditions and hygroscopicity (Petters and Kreidenweis, 2007;Petters et al, 2009), though this range may be slightly larger or smaller for fresh biomassburning particles due to these particles being initially more hydrophobic/hydrophilic (depending on fuel type) than typical ambient aerosol Engelhart et al, 2012;Petters and Kreidenweis, 2007). Furthermore, for constant emissions mass, a factor-of-2 change in diameter leads to a factor-of-8 change in number emissions, which may contribute to significant changes in CCN concentrations (Pierce et al, 2007;Spracklen et al, 2011).…”

Section: Biomass-burning Particlesmentioning

confidence: 99%

Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

et al. 2015

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Abstract. Biomass-burning aerosols contribute to aerosol radiative forcing on the climate system. The magnitude of this effect is partially determined by aerosol size distributions, which are functions of source fire characteristics (e.g. fuel type, MCE) and in-plume microphysical processing. The uncertainties in biomass-burning emission number-size distributions in climate model inventories lead to uncertainties in the CCN (cloud condensation nuclei) concentrations and forcing estimates derived from these models.The BORTAS-B (Quantifying the impact of BOReal forest fires on Tropospheric oxidants over the Atlantic using Aircraft and Satellite) measurement campaign was designed to sample boreal biomass-burning outflow over eastern Canada in the summer of 2011. Using these BORTAS-B data, we implement plume criteria to isolate the characteristic size distribution of aged biomass-burning emissions (aged ∼ 1-2 days) from boreal wildfires in northwestern Ontario. The composite median size distribution yields a single dominant accumulation mode with D pm = 230 nm (numbermedian diameter) and σ = 1.5, which are comparable to literature values of other aged plumes of a similar type. The organic aerosol enhancement ratios ( OA / CO) along the path of Flight b622 show values of 0.09-0.17 µg m −3 ppbv −1 (parts per billion by volume) with no significant trend with distance from the source. This lack of enhancement ratio increase/decrease with distance suggests no detectable net OA (organic aerosol) production/evaporation within the aged plume over the sampling period (plume age: 1-2 days), though it does not preclude OA production/loss at earlier stages. A Lagrangian microphysical model was used to determine an estimate of the freshly emitted size distribution corresponding to the BORTAS-B aged size distributions. The model was restricted to coagulation and dilution processes based on the insignificant net OA production/evaporation derived from the OA / CO enhancement ratios. We estimate that the young-plume median diameter was in the range of 59-94 nm with modal widths in the range of 1.7-2.8 (the ranges are due to uncertainty in the entrainment rate). Thus, the size of the freshly emitted particles is relatively unconstrained due to the uncertainties in the plume dilution rates.

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Cloud condensation nuclei activity of fresh primary and aged biomass burning aerosol

Cited by 121 publications

References 36 publications

Black carbon physical properties and mixing state in the European megacity Paris

Black carbon physical properties and mixing state in the European megacity Paris

Aerosol arriving on the Caribbean island of Barbados: physical properties and origin

Aged boreal biomass-burning aerosol size distributions from BORTAS 2011

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