A New Method to Determine the Number Concentrations of Refractory Black Carbon Ice Nucleating Particles

Levin, Ezra J. T.; McMeeking, G. R.; DeMott, Paul J.; McCluskey, Christina S.; Stockwell, Chelsea E.; Yokelson, Robert J.; Kreidenweis, Sonia M.

doi:10.1080/02786826.2014.977843

Cited by 14 publications

(31 citation statements)

References 64 publications

(88 reference statements)

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“…6b, the size distribution of SRFA is unaffected by the SP2 laser, indicating that this BrC proxy, which is highly colored, does not absorb appreciably at 1064 nm. Unlike the Snomax ® and SRFA, the mineral dust sample (ATD) used by Levin et al (2014) had a small incandesce signal in the SP2, which resulted in a new particle peak similar to rBC exhaust. Unlike rBC, however, its original size distribution was only minimally affected.…”

Section: Physical Properties Of Rbc Sp2 Exhaustmentioning

confidence: 99%

“…The general method has been previously described by Levin et al (2014) and Aiken et al (2016) and has been expanded in this work. Under normal operation, the SP2 operator sets only the sample and sheath flow.…”

Section: Sampling Sp2 Exhaustmentioning

confidence: 99%

“…Currently, the only technique to do so directly and in real time uses a Single Particle Soot Photometer (SP2) as a pre-filter to an online ice nucleation counter, the Continuous Flow Diffusion Chamber (CFDC; Levin et al, 2014). In the SP2 pre-filter, rBC is vaporized by a high-intensity 1064 nm laser; aerosol that do not absorb at 1064 nm, which encompasses most ambient non-rBC aerosol, pass through the cavity unaltered.…”

Section: Introductionmentioning

confidence: 99%

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Use of the Single Particle Soot Photometer (SP2) as a pre-filter for ice nucleation measurements: effect of particle mixing state and determination of SP2 conditions to fully vaporize refractory black carbon

Schill¹,

DeMott²,

Levin³

et al. 2018

Atmos. Meas. Tech.

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Abstract. Ice nucleation is a fundamental atmospheric process that impacts precipitation, cloud lifetimes, and climate. Challenges remain to identify and quantify the compositions and sources of ice-nucleating particles (INPs). Assessment of the role of black carbon (BC) as an INP is particularly important due to its anthropogenic sources and abundance at upper-tropospheric cloud levels. The role of BC as an INP, however, is unclear. This is, in part, driven by a lack of techniques that directly determine the contribution of refractory BC (rBC) to INP concentrations. One previously developed technique to measure this contribution uses the Single Particle Soot Photometer (SP2) as a pre-filter to an online icenucleating particle counter. In this technique, rBC particles are selectively heated to their vaporization temperature in the SP2 cavity by a 1064 nm laser. From previous work, however, it is unclear under what SP2 conditions, if any, the original rBC particles were fully vaporized. Furthermore, previous work also left questions about the effect of the SP2 laser on the ice-nucleating properties of several INP proxies and their mixtures with rBC.To answer these questions, we sampled the exhaust of an SP2 with a Scanning Mobility Particle Sizer and a Continuous Flow Diffusion Chamber. Using Aquadag ® as an rBC proxy, the effect of several SP2 instrument parameters on the size distribution and physical properties of particles in rBC SP2 exhaust were explored. We found that a high SP2 laser power (930 nW/(220 nm PSL)) is required to fully vaporize a ∼ 0.76 fg rBC particle. We also found that the exhaust particle size distribution is minimally affected by the SP2 sheath-to-sample ratio; the size of the original rBC particle, however, greatly influences the size distribution of the SP2 exhaust. The effect of the SP2 laser on the ice nucleation efficiency of Snomax ® , NX-illite, and Suwannee River Fulvic Acid was studied; these particles acted as proxies for biological, illite-rich mineral dust, and brown carbon INPs, respectively. The original size distribution and ice nucleation efficiency of all non-rBC proxies were unaffected by the SP2 laser. Furthermore, the ice nucleation efficiencies of all proxies were not affected when externally mixed with rBC. These proxies, however, always show a reduction in ice-nucleating ability when internally mixed with rBC. We end this work with recommendations for users who wish to use the SP2 as a pre-filter to remove large rBC particles from an aerosol stream.

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Section: Physical Properties Of Rbc Sp2 Exhaustmentioning

confidence: 99%

Section: Sampling Sp2 Exhaustmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Use of the Single Particle Soot Photometer (SP2) as a pre-filter for ice nucleation measurements: effect of particle mixing state and determination of SP2 conditions to fully vaporize refractory black carbon

Schill¹,

DeMott²,

Levin³

et al. 2018

Atmos. Meas. Tech.

View full text Add to dashboard Cite

show abstract

“…Unlike the Snomax® and SRFA, the mineral dust sample (ATD) used by Levin et al (2014) had a small incandesce signal in the SP2, which resulted in a new-particle peak similar to rBC exhaust. Unlike rBC, however, its original size distribution was only minimally affected.…”

Section: Effect Of Sp2 Laser On Snomax® Nx-illite and Srfa Size Dismentioning

confidence: 99%

“…The general method 30 has been previously described by Levin et al (2014) and Aiken et al (2016), and has been expanded in this work. Under normal operation, the SP2 operator sets only the sample and sheath flow.…”

Section: Sampling Sp2 Exhaustmentioning

confidence: 99%

Use of the Single Particle Soot Photometer (SP2) as a pre-filter for ice nucleation measurements: Effect of particle mixing state and determination of SP2 conditions to fully vaporize refractory black carbon

Schill¹,

DeMott²,

Levin³

et al. 2017

Preprint

View full text Add to dashboard Cite

Abstract. Ice nucleation is a fundamental atmospheric process that impacts precipitation, cloud lifetimes, and climate. Challenges remain to identify and quantify the compositions and sources of ice nucleating particles (INPs). Assessment of the role of black 10 carbon (BC) as an INP is particularly important due to its anthropogenic sources and abundance at upper tropospheric cloud levels.The role of BC as an INP, however, is unclear. This is, in part, driven by a lack of techniques that directly determine the contribution of refractory BC (rBC) to INP concentrations. One previously developed technique to measure this contribution uses the Single Particle Soot Photometer (SP2) as a pre-filter to an online ice nucleating particle counter. In this technique, rBC particles are selectively heated to their vaporization temperature in the SP2 cavity by a 1064-nm laser. From previous work, however, it is 15 unclear under what SP2 conditions, if any, that the original rBC particles were fully vaporized. Furthermore, previous work also left questions about the effect of the SP2 laser on the ice nucleating properties of several INP proxies and their mixtures with rBC.To answer these questions, we sampled the exhaust of an SP2 with a Scanning Mobility Particle Sizer and a Continuous Flow Diffusion Chamber. Using Aquadag® as an rBC proxy, the effect of several SP2 instrument parameters on the size distribution and physical properties of particles in rBC SP2 exhaust were explored. We found that a high SP2 laser fluence [930 20 nW/(220-nm PSL)] is required to fully vaporize a ~0.76 fg rBC particle. We also found that the exhaust particle size distribution is minimally affected by the SP2 sheath-to-sample ratio; the size of the original rBC particle, however, greatly influences the size distribution of the SP2 exhaust. The effect of the SP2 laser on the ice nucleation efficiency of Snomax®, NX-illite, and Suwannee River Fulvic Acid was studied; these particles acted as proxies for biological, illite-rich mineral dust, and brown carbon INPs, respectively. The original size distribution and ice nucleation efficiency of all non-rBC proxies were unaffected by the SP2 laser. 25 Furthermore, the ice nucleation efficiencies of all proxies were not affected when externally mixed with rBC. These proxies, however, always show a reduction in ice nucleating ability when internally mixed with rBC. We end this work with recommendations for users who wish to use the SP2 as a prefilter to remove large rBC particles from an aerosol stream.

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Ice‐nucleating particle emissions from photochemically aged diesel and biodiesel exhaust

Schill

Jathar

Kodros

et al. 2016

Geophysical Research Letters

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Immersion‐mode ice‐nucleating particle (INP) concentrations from an off‐road diesel engine were measured using a continuous‐flow diffusion chamber at −30°C. Both petrodiesel and biodiesel were utilized, and the exhaust was aged up to 1.5 photochemically equivalent days using an oxidative flow reactor. We found that aged and unaged diesel exhaust of both fuels is not likely to contribute to atmospheric INP concentrations at mixed‐phase cloud conditions. To explore this further, a new limit‐of‐detection parameterization for ice nucleation on diesel exhaust was developed. Using a global‐chemical transport model, potential black carbon INP (INPBC) concentrations were determined using a current literature INPBC parameterization and the limit‐of‐detection parameterization. Model outputs indicate that the current literature parameterization likely overemphasizes INPBC concentrations, especially in the Northern Hemisphere. These results highlight the need to integrate new INPBC parameterizations into global climate models as generalized INPBC parameterizations are not valid for diesel exhaust.

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A New Method to Determine the Number Concentrations of Refractory Black Carbon Ice Nucleating Particles

Cited by 14 publications

References 64 publications

Use of the Single Particle Soot Photometer (SP2) as a pre-filter for ice nucleation measurements: effect of particle mixing state and determination of SP2 conditions to fully vaporize refractory black carbon

Use of the Single Particle Soot Photometer (SP2) as a pre-filter for ice nucleation measurements: effect of particle mixing state and determination of SP2 conditions to fully vaporize refractory black carbon

Use of the Single Particle Soot Photometer (SP2) as a pre-filter for ice nucleation measurements: Effect of particle mixing state and determination of SP2 conditions to fully vaporize refractory black carbon

Ice‐nucleating particle emissions from photochemically aged diesel and biodiesel exhaust

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