HETEROGENEOUS NUCLEATION OF ICE BY MINERAL DUST INCLUSIONS IN AMMONIUM SULFATE PARTICLES

2001 ◽  
Vol 32 ◽  
pp. 295-296
Author(s):  
B. ZUBERI ◽  
A.K. BERTRAM ◽  
L.T. MOLINA ◽  
M.J. MOLINA
Keyword(s):  
Ammonium Sulfate ◽  
Heterogeneous Nucleation ◽  
Mineral Dust

scholarly journals Heterogeneous nucleation of a common atmospheric aerosol: Ammonium sulfate

1998 ◽  
Vol 25 (24) ◽  
pp. 4469-4472 ◽  
Author(s):  
Susan Oatis ◽  
Dan Imre ◽  
Robert McGraw ◽  
Jun Xu
Keyword(s):  
Ammonium Sulfate ◽  
Heterogeneous Nucleation ◽  
Atmospheric Aerosol

scholarly journals Single-particle characterization of aerosols collected at a remote site in the Amazonian rainforest and an urban site in Manaus, Brazil

2019 ◽  
Vol 19 (2) ◽  
pp. 1221-1240 ◽  
Author(s):  
Li Wu ◽  
Xue Li ◽  
HyeKyeong Kim ◽  
Hong Geng ◽  
Ricardo H. M. Godoi ◽  
...  
Keyword(s):  
Fly Ash ◽  
Ammonium Sulfate ◽  
Single Particle ◽  
Mineral Dust ◽  
Sea Salt ◽  
Urban Site ◽  
Formation Mechanisms ◽  
Remote Site ◽  
Sea Salts ◽  
Amazonian Rainforest

Abstract. In this study, aerosol samples collected at a remote site in the Amazonian rainforest and an urban site in Manaus, Brazil, were investigated on a single-particle basis using a quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA). A total of 23 aerosol samples were collected in four size ranges (0.25–0.5, 0.5–1.0, 1.0–2.0, and 2.0–4.0 µm) during the wet season in 2012 at two Amazon basin sites: 10 samples in Manaus, an urban area; and 13 samples at an 80 m high tower, located at the Amazon Tall Tower Observatory (ATTO) site in the middle of the rainforest, 150 km northeast of Manaus. The aerosol particles were classified into nine particle types based on the morphology on the secondary electron images (SEIs) together with the elemental concentrations of 3162 individual particles: (i) secondary organic aerosols (SOA); (ii) ammonium sulfate (AS); (iii) SOA and AS mixtures; (iv) aged mineral dust; (v) reacted sea salts; (vi) primary biological aerosol (PBA); (vii) carbon-rich or elemental carbon (EC) particles, such as soot, tarball, and char; (viii) fly ash; and (ix) heavy metal (HM, such as Fe, Zn, Ni, and Ti)-containing particles. In submicron aerosols collected at the ATTO site, SOA and AS mixture particles were predominant (50 %–94 % in relative abundance) with SOA and ammonium sulfate comprising 73 %–100 %. In supermicron aerosols at the ATTO site, aged mineral dust and sea salts (37 %–70 %) as well as SOA and ammonium sulfate (28 %–58 %) were abundant. PBAs were observed abundantly in the PM2−4 fraction (46 %), and EC and fly ash particles were absent in all size fractions. The analysis of a bulk PM0.25−0.5 aerosol sample from the ATTO site using Raman microspectrometry and attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) showed that ammonium sulfate, organics, and minerals are the major chemical species, which is consistent with the ED-EPMA results. In the submicron aerosols collected in Manaus, either SOA and ammonium sulfate (17 %–80 %) or EC particles (6 %–78 %) were dominant depending on the samples. In contrast, aged mineral dust, reacted sea salt, PBA, SOA, ammonium sulfate, and EC particles comprised most of the supermicron aerosols collected in Manaus. The SOA, ammonium sulfate, and PBAs were mostly of a biogenic origin from the rainforest, whereas the EC and HM-containing particles were of an anthropogenic origin. Based on the different contents of SOA, ammonium sulfate, and EC particles among the samples collected in Manaus, a considerable influence of the rainforest over the city was observed. Aged mineral dust and reacted sea-salt particles, including mineral dust mixed with sea salts probably during long-range transatlantic transport, were abundant in the supermicron fractions at both sites. Among the aged mineral dust and reacted sea-salt particles, sulfate-containing ones outnumbered those containing nitrates and sulfate + nitrate in the ATTO samples. In contrast, particles containing sulfate + nitrate were comparable in number to particles containing sulfate only in the Manaus samples, indicating the different sources and formation mechanisms of secondary aerosols, i.e., the predominant presence of sulfate at the ATTO site from mostly biogenic emissions and the elevated influences of nitrates from anthropogenic activities at the Manaus site.

scholarly journals Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals

2011 ◽  
Vol 11 (7) ◽  
pp. 3527-3541 ◽  
Author(s):  
P. Kumar ◽  
I. N. Sokolik ◽  
A. Nenes
Keyword(s):  
Ammonium Sulfate ◽  
Mineral Dust ◽  
Cloud Condensation Nuclei ◽  
Dust Particles ◽  
Droplet Growth ◽  
Condensation Nuclei ◽  
Activation Kinetics ◽  
Droplet Activation ◽  
Kinetics Of ◽  
Ccn Activity

Abstract. This study reports laboratory measurements of cloud condensation nuclei (CCN) activity and droplet activation kinetics of aerosols dry generated from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. Based on the observed dependence of critical supersaturation, sc, with particle dry diameter, Ddry, we found that FHH (Frenkel, Halsey and Hill) adsorption activation theory is a far more suitable framework for describing fresh dust CCN activity than Köhler theory. One set of FHH parameters (AFHH ∼ 2.25 ± 0.75, BFHH ∼ 1.20 ± 0.10) can adequately reproduce the measured CCN activity for all species considered, and also explains the large range of hygroscopicities reported in the literature. Based on a threshold droplet growth analysis, mineral dust aerosols were found to display retarded activation kinetics compared to ammonium sulfate. Comprehensive simulations of mineral dust activation and growth in the CCN instrument suggest that this retardation is equivalent to a reduction of the water vapor uptake coefficient (relative to that for calibration ammonium sulfate aerosol) by 30–80%. These results suggest that dust particles do not require deliquescent material to act as CCN in the atmosphere.

scholarly journals Single-particle characterization of aerosols collected at a remote site in the Amazonian rainforest and an urban site in Manaus, Brazil

2018 ◽  
Author(s):  
Li Wu ◽  
Xue Li ◽  
Hye Kyeong Kim ◽  
Hong Geng ◽  
Ricardo H. M. Godoi ◽  
...  
Keyword(s):  
Fly Ash ◽  
Ammonium Sulfate ◽  
Single Particle ◽  
Mineral Dust ◽  
Sea Salt ◽  
Urban Site ◽  
Formation Mechanisms ◽  
Remote Site ◽  
Sea Salts ◽  
Amazonian Rainforest

Abstract. In this study, aerosol samples collected at a remote site in the Amazonian rainforest and an urban site in Manaus, Brazil, were investigated on a single particle basis using a quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA). Twenty-three aerosol samples were collected in four size ranges (0.25–0.5, 0.5–1.0, 1.0–2.0, and 2.0–4.0 µm) during the wet season in 2012 at two Amazon basin sites: 10 samples in Manaus, an urban area; and 13 samples at an 80-m high tower, located at the Amazon Tall Tower Observatory (ATTO) site in the middle of the rainforest, 150 km northeast of Manaus. The aerosol particles were classified into nine particle types based on the morphology on the secondary electron images (SEIs) together with the elemental concentrations of 3,162 individual particles: (i) secondary organic aerosols (SOA), (ii) ammonium sulfate (AS), (iii) SOA and AS mixtures, (iv) aged mineral dust, (v) reacted sea-salts, (vi) primary biological aerosol (PBA), (vii) carbon-rich or elemental carbon (EC) particles, such as soot, tar ball, and char, (viii) fly ash, and (ix) heavy metal (HM, such as Fe, Zn, Ni, and Ti)-containing particles. In submicron aerosols collected at the ATTO site, SOA and AS mixture particles were predominant (50–94 % in relative abundance) with SOA and ammonium sulfate comprising 73–100 %. In supermicron aerosols at the ATTO site, aged mineral dust and sea-salts (37–70 %) as well as SOA and ammonium sulfate (28–58 %) were abundant. PBAs were observed abundantly in the PM2–4 fraction (46 %), and EC and fly ash particles were absent in all size fractions. The analysis of a bulk PM0.25–0.5 aerosol sample from the ATTO site using Raman microspectrometry and attenuated total reflection Fourier transform infrared spectroscopy showed that ammonium sulfate, organics, and minerals are the major chemical species, which is consistent with the ED-EPMA results. In the submicron aerosols collected in Manaus, either SOA and ammonium sulfate (17–80 %) or EC particles (6–78 %) were dominant depending on the samples. In contrast, aged mineral dust, reacted sea-salt, PBA, SOA, ammonium sulfate, and EC particles comprised most of the supermicron aerosols collected in Manaus. The SOA, ammonium sulfate, and PBAs were mostly of a biogenic origin from the rainforest, whereas the EC and HM-containing particles were of an anthropogenic origin. Aged mineral dust and reacted sea-salt particles, including mineral dust mixed with sea-salts probably during long-range transatlantic transport, were abundant in the supermicron fractions at both sites. Among the aged mineral dust and reacted sea-salt particles, sulfate-containing ones outnumbered those containing nitrates and sulfate+nitrate in the ATTO samples. In contrast, particles containing sulfate+nitrate were comparable in number to particles containing sulfate only in the Manaus samples, indicating the different sources and formation mechanisms of secondary aerosols, i.e., the predominant presence of sulfate at the ATTO site from mostly biogenic emissions and the elevated influences of nitrates from anthropogenic activities at the Manaus site.

scholarly journals Measurements of cloud condensation nuclei activity and droplet activation kinetics of fresh unprocessed regional dust samples and minerals

2010 ◽  
Vol 10 (12) ◽  
pp. 31039-31081 ◽  
Author(s):  
P. Kumar ◽  
I. N. Sokolik ◽  
A. Nenes
Keyword(s):  
Ammonium Sulfate ◽  
Mineral Dust ◽  
Cloud Condensation Nuclei ◽  
Dust Particles ◽  
Droplet Growth ◽  
Condensation Nuclei ◽  
Activation Kinetics ◽  
Droplet Activation ◽  
Kinetics Of ◽  
Ccn Activity

Abstract. This study reports laboratory measurements of cloud condensation nuclei (CCN) activity and droplet activation kinetics of aerosols dry-generated from clays, calcite, quartz, and desert soil samples from Northern Africa, East Asia/China, and Northern America. Based on the observed dependence of critical supersaturation, sc, with particle dry diameter, Ddry, we find that FHH adsorption activation theory is a far more suitable framework for describing fresh dust CCN activity than Köhler theory. One set of FHH parameters (AFFH ~ 2.25 ± 0.75, BFFH ~ 1.20 ± 0.10) can adequately reproduce the measured CCN activity for all species considered, and also explains the large range of hygroscopicities reported in the literature. Based on threshold droplet growth analysis, mineral dust aerosols were found to display retarded activation kinetics compared to ammonium sulfate. Comprehensive simulations of mineral dust activation and growth in the CCN instrument suggest that this retardation is equivalent to a reduction of the water vapor uptake coefficient (relative to that for calibration ammonium sulfate aerosol) by 30–80%. These results suggest that dust particles do not require deliquescent material to act as CCN in the atmosphere.

scholarly journals Heterogeneous nucleation of ice in (NH4)2SO4-H2O particles with mineral dust immersions

2002 ◽  
Vol 29 (10) ◽  
pp. 142-1-142-4 ◽  
Author(s):  
Bilal Zuberi ◽  
Allan K. Bertram ◽  
Christopher A. Cassa ◽  
Luisa T. Molina ◽  
Mario J. Molina
Keyword(s):  
Heterogeneous Nucleation ◽  
Mineral Dust

scholarly journals Detailed cloud resolving model simulations of the impacts of Saharan air layer dust on tropical deep convection – Part 1: Dust acts as ice nuclei

2010 ◽  
Vol 10 (5) ◽  
pp. 12907-12952 ◽  
Author(s):  
W. Gong ◽  
Q. Min ◽  
R. Li ◽  
A. Teller ◽  
E. Joseph ◽  
...  
Keyword(s):  
Water Vapor ◽  
Heterogeneous Nucleation ◽  
Mineral Dust ◽  
Deep Convection ◽  
Number Concentration ◽  
Middle Troposphere ◽  
Saharan Air Layer ◽  
Ice Nuclei ◽  
Tropical Deep Convection ◽  
Cloud Resolving Model

Abstract. Observational studies suggest that the Saharan Air Layer (SAL), an elevated layer (850–500 hPa) of Saharan air and mineral dust, has strong impacts on the microphysical as well as dynamical properties of tropical deep convective cloud systems along its track. In this case study, numerical simulations using a two-dimensional Detailed Cloud Resolving Model (DCRM) were carried out to investigate the dust-cloud interactions in the tropical deep convection, focusing on the dust role as Ice Nuclei (IN). The simulations showed that mineral dust considerably enhanced heterogeneous nucleation and freezing at temperatures warmer than −40 °C, resulting in more ice hydrometeors number concentration and reduced precipitating size of ice particles. Because of the lower in the saturation over ice as well as more droplet freezing, total latent heating increased, and consequently the updraft velocity was stronger. On the other hand, the increased ice deposition consumed more water vapor at middle troposphere, which induces a competition for water vapor between heterogeneous and homogeneous freezing and nucleation. As a result, dust suppressed the homogeneous droplet freezing and nucleation due to the heterogeneous droplet freezing and the weakened transport of water vapor at lower stratosphere, respectively. These effects led to decreased number concentration of ice cloud particles in the upper troposphere, and consequently lowered the cloud top height during the stratus precipitating stage. Acting as IN, mineral dust also influenced precipitation in deep convection. It initiated earlier the collection because dust-related heterogeneous nucleation and freezing at middle troposphere occur earlier than homogeneous nucleation at higher altitudes. Nevertheless, the convective precipitation was suppressed by reduced collection of large graupel particles and insufficient fallout related to decreased sizes of precipitating ice hydrometeors. On the contrary, dust increased the precipitation in stratiform precipitation through deposition growth. Overall, the comprehensive effects of mineral dust suppressed the precipitation by up to 22%.

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