“…All 3 modes are assumed to have the same composition as each other based on the filter measurements from 7 August: 76% organic, 4% BC (an insoluble organic with index of refraction=(1.82, 0.74) and density=2 g cm −3 ) and 20% ammonium sulphate. Particles are assumed to be internally mixed based on hygroscopic growth measurements at this site (Aklilu and Mozurkewich, 2004;Shantz et al, 2004). Figure 10 shows the scattering cross-sectional area from the model output compared with the voltage from the CCNc observations.…”
Section: Simulations Of 7 August 2001 From the Golden Ears Studymentioning
confidence: 99%
“…The Golden Ears provincial park study was part of the Pa- Table 4 summarizes the measurements made during this project that have been discussed previously by Shantz et al (2004). Note all times mentioned with respect to the Golden Ears study are in local time (i.e.…”
Section: Golden Ears Provincial Park Field Studymentioning
confidence: 99%
“…The increased mass is explained by the condensation of secondary organic aerosol as suggested by the gradual increase in particle mass from 9-11 August. Most of the additional material on 11 August is suspected to be due to the oxidation of monoterpenes as measured concentrations of a known product of terpene oxidation, cis-pinonic acid, also increased during this period Shantz et al, 2004). Each mode is assumed to have the same composition, an internal mixture of 85% organic, 2% BC and 13% ammonium sulphate (note that the sum of all inorganic ions is assumed to be ammonium sulphate).…”
Section: Simulations Of 7 August 2001 From the Golden Ears Studymentioning
confidence: 99%
“…Larger particle size distributions were measured using an optical particle counter, a PMS Passive Cavity Aerosol Spectrometer Probe (PCASP). Both the SMPS and PCASP N. C. Shantz et al: Droplet growth on organic aerosols from field measurements 5871 are used in the two field projects, the C-SOLAS study and the Golden Ears study (see Phinney et al, 2006 andShantz et al, 2004, respectively, for further details).…”
Section: Particle Size Distributionsmentioning
confidence: 99%
“…The BC and OC concentrations were determined by a modified NIOSH method using a Sunset Labs Thermal Optical Transmission Instrument Sharma et al, 2002). Water-soluble organic carbon (WSOC) was also measured in samples from the quartz filters as described by Shantz et al (2004).…”
Abstract. Organic matter represents an important fraction of the fine particle aerosol, yet our knowledge of the roles of organics in the activation of aerosol particles into cloud droplets is poor. A cloud condensation nucleus (CCN) counter is used to examine the relative growth rates of cloud droplets for case studies from field measurements on the North Pacific Ocean and in a coniferous forest. A model of the condensational growth of water droplets, on particles dissolving according to their solubility in water, is used to simulate the initial scattering of the droplets as they grow in the CCN counter. Simulations of the growth rates of fine particles sampled in the marine boundary layer of the North Pacific Ocean shows no evidence of natural marine organic material contributing to the CCN water uptake but there is an indication of an influence from organics from diesel ship emissions on the size distribution of sulphate and the ability of these particles to act as CCN. Simulations of the observations of water uptake on biogenic organic aerosol particles sampled in a coniferous forest indicate an impact of the organic on the water uptake rates, but one that is still smaller than that of pure sulphate. The existence of organics becomes important in determining the water uptake as the organic mass increases relative to sulphate. The values of the organic component of the hygroscopicity parameter κ that describes the CCN activity were found to be negligible for the marine particles and 0.02-0.05 for the forest particles.
“…All 3 modes are assumed to have the same composition as each other based on the filter measurements from 7 August: 76% organic, 4% BC (an insoluble organic with index of refraction=(1.82, 0.74) and density=2 g cm −3 ) and 20% ammonium sulphate. Particles are assumed to be internally mixed based on hygroscopic growth measurements at this site (Aklilu and Mozurkewich, 2004;Shantz et al, 2004). Figure 10 shows the scattering cross-sectional area from the model output compared with the voltage from the CCNc observations.…”
Section: Simulations Of 7 August 2001 From the Golden Ears Studymentioning
confidence: 99%
“…The Golden Ears provincial park study was part of the Pa- Table 4 summarizes the measurements made during this project that have been discussed previously by Shantz et al (2004). Note all times mentioned with respect to the Golden Ears study are in local time (i.e.…”
Section: Golden Ears Provincial Park Field Studymentioning
confidence: 99%
“…The increased mass is explained by the condensation of secondary organic aerosol as suggested by the gradual increase in particle mass from 9-11 August. Most of the additional material on 11 August is suspected to be due to the oxidation of monoterpenes as measured concentrations of a known product of terpene oxidation, cis-pinonic acid, also increased during this period Shantz et al, 2004). Each mode is assumed to have the same composition, an internal mixture of 85% organic, 2% BC and 13% ammonium sulphate (note that the sum of all inorganic ions is assumed to be ammonium sulphate).…”
Section: Simulations Of 7 August 2001 From the Golden Ears Studymentioning
confidence: 99%
“…Larger particle size distributions were measured using an optical particle counter, a PMS Passive Cavity Aerosol Spectrometer Probe (PCASP). Both the SMPS and PCASP N. C. Shantz et al: Droplet growth on organic aerosols from field measurements 5871 are used in the two field projects, the C-SOLAS study and the Golden Ears study (see Phinney et al, 2006 andShantz et al, 2004, respectively, for further details).…”
Section: Particle Size Distributionsmentioning
confidence: 99%
“…The BC and OC concentrations were determined by a modified NIOSH method using a Sunset Labs Thermal Optical Transmission Instrument Sharma et al, 2002). Water-soluble organic carbon (WSOC) was also measured in samples from the quartz filters as described by Shantz et al (2004).…”
Abstract. Organic matter represents an important fraction of the fine particle aerosol, yet our knowledge of the roles of organics in the activation of aerosol particles into cloud droplets is poor. A cloud condensation nucleus (CCN) counter is used to examine the relative growth rates of cloud droplets for case studies from field measurements on the North Pacific Ocean and in a coniferous forest. A model of the condensational growth of water droplets, on particles dissolving according to their solubility in water, is used to simulate the initial scattering of the droplets as they grow in the CCN counter. Simulations of the growth rates of fine particles sampled in the marine boundary layer of the North Pacific Ocean shows no evidence of natural marine organic material contributing to the CCN water uptake but there is an indication of an influence from organics from diesel ship emissions on the size distribution of sulphate and the ability of these particles to act as CCN. Simulations of the observations of water uptake on biogenic organic aerosol particles sampled in a coniferous forest indicate an impact of the organic on the water uptake rates, but one that is still smaller than that of pure sulphate. The existence of organics becomes important in determining the water uptake as the organic mass increases relative to sulphate. The values of the organic component of the hygroscopicity parameter κ that describes the CCN activity were found to be negligible for the marine particles and 0.02-0.05 for the forest particles.
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