Soot reference materials for instrument calibration and intercomparisons: a workshop summary with recommendations

Baumgardner, Darrel; Popovicheva, Olga; Allan, J. D.; Bernardoni, V.; Cao, Junji; Cavalli, F.; Cozic, J.; Diapouli, Evangelia; Eleftheriadis, Konstantinos; Genberg, P. J.; González, Carlos; Gysel, M.; John, Astrid C.; Kirchstetter, Thomas W.; Kuhlbusch, Thomas A. J.; Laborde, M.; Lack, D. A.; Müller, Thomas; Nießner, Reinhard; Petzold, A.; Piazzalunga, A.; Putaud, Jean‐Philippe; Schwarz, J. P.; Sheridan, Patrick J.; Subramanian, R.; Swietlicki, Erik; Valli, G.; Vecchi, R.; Viana, Mar

doi:10.5194/amt-5-1869-2012

Cited by 209 publications

(196 citation statements)

References 78 publications

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“…The registration filter is not itself a calibration standard whose absorptance is independently known a priori. A 2011 workshop described by Baumgardner et al (2012) identified a general lack of such standards, concluding that "there are no procedures to calibrate filter-based instruments that use the measurement of light attenuation to derive the absorption coefficient." Optical components are available with certified values of reflectance or transmittance, but these standards do not mimic the observed scattering phase functions of filter media and filter samples.…”

Section: Methods and Calibrationmentioning

confidence: 99%

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

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Trzepla

Hyslop

et al. 2016

Aerosol Science and Technology

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Section: Methods and Calibrationmentioning

confidence: 99%

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

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Trzepla

Hyslop

et al. 2016

Aerosol Science and Technology

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“…Refractory black carbon (BC) concentrations were also measured using a DMT single-particle soot photometer (SP2; Stephens et al, 2003;Schwarz et al, 2010), with optics and electronics upgraded to be functionally identical to the current SP2 model D. The SP2 was calibrated with Aquadag as recommended by Baumgardner et al (2012) and Laborde et al (2012). Further details on the aerosol instrumentation and measurements will be provided in a future manuscript.…”

Section: Aerosol Instrumentationmentioning

confidence: 99%

Observations of cloud microphysics and ice formation during COPE

et al. 2016

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Abstract. We present microphysical observations of cumulus clouds measured over the southwest peninsula of the UK during the COnvective Precipitation Experiment (COPE) in August 2013, which are framed into a wider context using ground-based and airborne radar measurements. Two lines of cumulus clouds formed in the early afternoon along convergence lines aligned with the peninsula. The lines became longer and broader during the afternoon due to new cell formation and stratiform regions forming downwind of the convective cells. Ice concentrations up to 350 L −1 , well in excess of the expected ice nuclei (IN) concentrations, were measured in the mature stratiform regions, suggesting that secondary ice production was active.Detailed sampling focused on an isolated liquid cloud that glaciated as it matured to merge with a band of cloud downwind. In the initial cell, drizzle concentrations increased from ∼ 0.5 to ∼ 20 L −1 in around 20 min. Ice concentrations developed up to a few per litre, which is around the level expected of primary IN. The ice images were most consistent with freezing drizzle, rather than smaller cloud drops or interstitial IN forming the first ice.As new cells emerged in and around the cloud, ice concentrations up to 2 orders of magnitude higher than the predicted IN concentrations developed, and the cloud glaciated over a period of 12-15 min. Almost all of the first ice particles to be observed were frozen drops, while vapour-grown ice crystals were dominant in the latter stages. Our observations are consistent with the production of large numbers of small secondary ice crystals/fragments, by a mechanism such as Hallett-Mossop or droplets shattering upon freezing. Some of the small ice froze drizzle drops on contact, while others grew more slowly by vapour deposition. Graupel and columns were seen in cloud penetrations up to the −12 • C level, though many ice particles were mixed habit due to riming and growth by vapour deposition at multiple temperatures.Our observations demonstrate that the freezing of drizzle/raindrops is an important process that dominates the formation of large ice in the intermediate stages of cloud development. As these frozen drops were the first precipitation observed, interactions between the warm-rain and secondary ice production processes appear to be key to determining the timing and location of precipitation.

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“…The incandescence signal was calibrated (three times, at the beginning, half way through and at the end of the measurement campaign) using mobility size selected fullerene soot particles (Alpha Aesar; #FS12S011) which is recommended for SP2 calibration as it gives similar SP2 responses as ambient rBC Baumgardner et al, 2012;Laborde et al, 2012a). The fullerene soot particles were selected by mobility diameter using a differential mobility analyser (DMA) and the corresponding particle masses were calculated using the effective density data provided in .…”

Section: Calibrationmentioning

confidence: 99%

“…The scattering signal was calibrated twice (at the beginning and half way through the measurement campaign) using spherical polystyrene latex size standards with a diameter of 269 nm (Thermo Scientific, formerly Duke Scientific). More details on SP2 calibration and calibration standard material can be found in Baumgardner et al (2012), Laborde et al (2012b) and .…”

Section: Calibrationmentioning

confidence: 99%

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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Soot reference materials for instrument calibration and intercomparisons: a workshop summary with recommendations

Cited by 209 publications

References 78 publications

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

A critical review of filter transmittance measurements for aerosol light absorption, and de novo calibration for a decade of monitoring on PTFE membranes

Observations of cloud microphysics and ice formation during COPE

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

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