scholarly journals In-cloud formation of secondary species in iron-containing particles

2019 ◽  
Vol 19 (2) ◽  
pp. 1195-1206 ◽  
Author(s):  
Qinhao Lin ◽  
Xinhui Bi ◽  
Guohua Zhang ◽  
Yuxiang Yang ◽  
Long Peng ◽  
...  
Keyword(s):  
Southern China ◽  
Formation Rate ◽  
Cloud Formation ◽  
Dust Particles ◽  
Cloud Droplets ◽  
Aerosol Mass Spectrometer ◽  
Secondary Species ◽  
Cloud Processing ◽  
Aerosol Mass ◽  
Combustion Sources

Abstract. The increase in secondary species through cloud processing potentially increases aerosol iron (Fe) bioavailability. In this study, a ground-based counterflow virtual impactor coupled with a real-time single-particle aerosol mass spectrometer was used to characterize the formation of secondary species in Fe-containing cloud residues (dried cloud droplets) at a mountain site in southern China for nearly 1 month during the autumn of 2016. Fe-rich, Fe-dust, Fe-elemental carbon (Fe-EC), and Fe-vanadium (Fe-V) cloud residual types were obtained in this study. The Fe-rich particles, related to combustion sources, contributed 84 % (by number) to the Fe-containing cloud residues, and the Fe-dust particles represented 12 %. The remaining 4 % consisted of the Fe-EC and Fe-V particles. It was found that above 90 % (by number) of Fe-containing particles had already contained sulfate before cloud events, leading to no distinct change in number fraction (NF) of sulfate during cloud events. Cloud processing contributed to the enhanced NFs of nitrate, chloride, and oxalate in the Fe-containing cloud residues. However, the in-cloud formation of nitrate and chloride in the Fe-rich type was less obvious relative to the Fe-dust type. The increased NF of oxalate in the Fe-rich cloud residues was produced via aqueous oxidation of oxalate precursors (e.g., glyoxylate). Moreover, Fe-driven Fenton reactions likely increase the formation rate of aqueous-phase OH, improving the conversion of the precursors to oxalate in the Fe-rich cloud residues. During daytime, the decreased NF of oxalate in the Fe-rich cloud residues was supposed to be due to the photolysis of Fe-oxalate complexes. This work emphasizes the role of combustion Fe sources in participating in cloud processing and has important implications for evaluating Fe bioavailability from combustion sources during cloud processing.

scholarly journals In-cloud formation of secondary species in iron-containing particles

2018 ◽  
Author(s):  
Qinhao Lin ◽  
Xinhui Bi ◽  
Guohua Zhang ◽  
Yuxiang Yang ◽  
Long Peng ◽  
...  
Keyword(s):  
Southern China ◽  
Cloud Formation ◽  
Dust Particles ◽  
Cloud Droplets ◽  
Aerosol Mass Spectrometer ◽  
Secondary Species ◽  
Cloud Processing ◽  
Aerosol Mass ◽  
Combustion Sources

Abstract. The increase of secondary species through cloud processing potentially increases aerosol iron (Fe) bioavailability. In this study, a ground-based counterflow virtual impactor coupled with a real-time single-particle aerosol mass spectrometer was used to characterize the formation of secondary species in Fe-containing cloud residues (dried cloud droplets) at a mountain site in southern China for nearly one month during the autumn of 2016. Fe-rich, Fe-dust, Fe-elemental carbon (Fe-EC), and Fe-vanadium (Fe-V) cloud residual types were obtained in this study. The Fe-rich particles, related to combustion sources, contributed 84 % to the Fe-containing cloud residues, and the Fe-dust particles represented 12 %. The remaining 4 % consisted of the Fe-EC and Fe-V particles. It was found that extremely high amounts of sulfate had already accumulated on the Fe-containing particles before cloud events, leading to no distinct changes in sulfate during cloud events. Cloud processing contributed to the enhancement of nitrate, chloride, and oxalate in the Fe-containing cloud residues. However, the in-cloud formation of nitrate and chloride in the Fe-rich type was less obvious relative to the Fe-dust type. The enhancement of oxalate in the Fe-rich cloud residues was produced via aqueous oxidation of oxalate precursors (e.g., glyoxylate). Moreover, Fe chemistry involved in the Fenton reaction further promoted the conversion of the oxalate precursors to oxalate during cloud events, although the photolysis of Fe-oxalate complexes also existed in the Fe-rich cloud residues. This work emphasizes the role of combustion Fe sources in participating in cloud processing and has important implications for evaluating Fe bioavailability from combustion sources during cloud processing.

scholarly journals Cloud processing of mineral dust: direct comparison of cloud residual and clear sky particles during AMMA aircraft campaign in summer 2006

2010 ◽  
Vol 10 (3) ◽  
pp. 1057-1069 ◽  
Author(s):  
A. Matsuki ◽  
A. Schwarzenboeck ◽  
H. Venzac ◽  
P. Laj ◽  
S. Crumeyrolle ◽  
...  
Keyword(s):  
Electron Microscope ◽  
Mineral Dust ◽  
Large Fraction ◽  
Dust Particles ◽  
Cloud Droplets ◽  
Secondary Species ◽  
Cloud Processing ◽  
Clear Sky ◽  
Multidisciplinary Analysis ◽  
Dust Component

Abstract. In order to gain insights into the characteristics of the mineral dust particles incorporated in the actual cloud droplets and the related cloud processing, the French ATR-42 research aircraft equipped both with a counterflow virtual impactor (CVI) and community aerosol inlet was deployed in Niamey, Niger (13°30' N, 02°05' E) in August 2006 within the framework of the African Monsoon Multidisciplinary Analysis (AMMA) project. Cloud residual and clear-sky particles were collected separately and analyzed individually using a transmission electron microscope (TEM) and a scanning electron microscope coupled with an energy dispersive X-ray spectroscopy (SEM-EDX). The analysis revealed interesting characteristics on the coarse dust particles (Dp>1μm), particularly those which likely had acted as CCN. Traces of heterogeneously formed secondary sulfate, chloride and nitrate were found on many dust particles (though fraction of sulfate may be present in the form of gypsum as primary dust component). These secondary species were particularly enhanced in clouds (i.e. cloud processing). The study illustrates that calcium-rich particles assumed to be carbonates (Calcite, Dolomite) contained the secondary species in significantly larger frequency and amount than the silicates (Quartz, Feldspar, Mica, Clay), suggesting that they represent the most reactive fraction of the mineral dust. A surprisingly large fraction of the Ca-rich particles were already found in deliquesced form even in clear-sky conditions, most probably reflecting their extreme hygroscopicity, resulting from their reaction with HNO3 gas. Both silicate and Ca-rich particles were found dominant among the supermicron cloud residues, and they were supposed to be those previously activated as CCN. It is highly probable that the observed formation of soluble materials enhanced their cloud nucleating abilities.

scholarly journals Microphysical processing of aerosol particles in orographic clouds

2015 ◽  
Vol 15 (16) ◽  
pp. 9217-9236 ◽  
Author(s):  
S. Pousse-Nottelmann ◽  
E. M. Zubler ◽  
U. Lohmann
Keyword(s):  
Cloud Droplet ◽  
Number Concentration ◽  
Mixed Phase ◽  
Cloud Formation ◽  
Small Scale ◽  
Cloud Droplets ◽  
Aerosol Mass ◽  
Aerosol Processing ◽  
Orographic Clouds ◽  
Aerosol Scavenging

Abstract. An explicit and detailed treatment of cloud-borne particles allowing for the consideration of aerosol cycling in clouds has been implemented into COSMO-Model, the regional weather forecast and climate model of the Consortium for Small-scale Modeling (COSMO). The effects of aerosol scavenging, cloud microphysical processing and regeneration upon cloud evaporation on the aerosol population and on subsequent cloud formation are investigated. For this, two-dimensional idealized simulations of moist flow over two bell-shaped mountains were carried out varying the treatment of aerosol scavenging and regeneration processes for a warm-phase and a mixed-phase orographic cloud. The results allowed us to identify different aerosol cycling mechanisms. In the simulated non-precipitating warm-phase cloud, aerosol mass is incorporated into cloud droplets by activation scavenging and released back to the atmosphere upon cloud droplet evaporation. In the mixed-phase cloud, a first cycle comprises cloud droplet activation and evaporation via the Wegener–Bergeron–Findeisen (WBF) process. A second cycle includes below-cloud scavenging by precipitating snow particles and snow sublimation and is connected to the first cycle via the riming process which transfers aerosol mass from cloud droplets to snowflakes. In the simulated mixed-phase cloud, only a negligible part of the total aerosol mass is incorporated into ice crystals. Sedimenting snowflakes reaching the surface remove aerosol mass from the atmosphere. The results show that aerosol processing and regeneration lead to a vertical redistribution of aerosol mass and number. Thereby, the processes impact the total aerosol number and mass and additionally alter the shape of the aerosol size distributions by enhancing the internally mixed/soluble Aitken and accumulation mode and generating coarse-mode particles. Concerning subsequent cloud formation at the second mountain, accounting for aerosol processing and regeneration increases the cloud droplet number concentration with possible implications for the ice crystal number concentration.

scholarly journals The single-particle mixing state and cloud scavenging of black carbon: a case study at a high-altitude mountain site in southern China

2017 ◽  
Vol 17 (24) ◽  
pp. 14975-14985 ◽  
Author(s):  
Guohua Zhang ◽  
Qinhao Lin ◽  
Long Peng ◽  
Xinhui Bi ◽  
Duohong Chen ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
Southern China ◽  
Cloud Droplet ◽  
Mixing State ◽  
Cloud Droplets ◽  
Aerosol Mass ◽  
Mountain Site ◽  
Cloud Scavenging ◽  
Scavenging Efficiency

Abstract. In the present study, a ground-based counterflow virtual impactor (GCVI) was used to sample cloud droplet residual (cloud RES) particles, while a parallel PM2.5 inlet was used to sample cloud-free or cloud interstitial (cloud INT) particles. The mixing state of black carbon (BC)-containing particles and the mass concentrations of BC in the cloud-free, RES and INT particles were investigated using a single-particle aerosol mass spectrometer (SPAMS) and two aethalometers, respectively, at a mountain site (1690 m a. s. l. ) in southern China. The measured BC-containing particles were extensively internally mixed with sulfate and were scavenged into cloud droplets (with number fractions of 0.05–0.45) to a similar (or slightly lower) extent as all the measured particles (0.07–0.6) over the measured size range of 0.1–1.6 µm. The results indicate the preferential activation of larger particles and/or that the production of secondary compositions shifts the BC-containing particles towards larger sizes. BC-containing particles with an abundance of both sulfate and organics were scavenged less than those with sulfate but limited organics, implying the importance of the mixing state on the incorporation of BC-containing particles into cloud droplets. The mass scavenging efficiency of BC with an average of 33 % was similar for different cloud events independent of the air mass. This is the first time that both the mixing state and cloud scavenging of BC in China have been reported. Our results would improve the knowledge on the concentration, mixing state, and cloud scavenging of BC in the free troposphere.

scholarly journals New particle formation from the oxidation of direct emissions of pine seedlings

2009 ◽  
Vol 9 (2) ◽  
pp. 8223-8260 ◽  
Author(s):  
L. Q. Hao ◽  
P. Yli-Pirilä ◽  
P. Tiitta ◽  
S. Romakkaniemi ◽  
P. Vaattovaara ◽  
...  
Keyword(s):  
Scots Pine ◽  
Formation Rate ◽  
Particle Formation ◽  
Effective Density ◽  
Particle Nucleation ◽  
New Particle Formation ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Pine Seedlings ◽  
Condensational Growth

Abstract. Measurements of particle formation following the gas phase oxidation of volatile organic compounds (VOCs) emitted by Scots pine (Pinus sylvestris L.) seedlings are reported. Particle nucleation and condensational growth both from ozone (O3) and hydroxyl radical (OH) initiated oxidation of pine emissions (about 20–120 ppb) were investigated in a~smog chamber. During experiments, tetramethylethylene (TME) and 2-butanol were added to control the concentrations of O3 and OH. Particle nucleation and condensational growth rates were interpreted with a chemical kinetics model. Scots pine emissions mainly included α-pinene, β-pinene, Δ3-carene, limonene, myrcene, β-phellandrene and isoprene, composing more than 95% of total emissions. Modeled OH concentration in the O3+OH induced experiments was at a level of ~106 molecular cm−3. Our results demonstrate that OH-initiated oxidation of VOCs plays an important role in the nucleation process during the initial new particle formation stage. The highest average nucleation rate of 360 cm−3 s−1 was observed for the OH-dominated nucleation events and the lowest aerosol mean formation rate less than 0.5 cm−3 s−1 for the case with only O3 present as an oxidant. On the other hand, ozonolysis of monoterpenes appears to be much more efficient to the aerosol growth process following nucleation. Higher contributions of more oxygenated products to the SOA mass loadings from OH-dominating oxidation systems were found as compared to the ozonolysis systems. Comparison of mass and volume distributions from the aerosol mass spectrometer and differential mobility analyzer yields estimated effective density of these SOA to be 1.34±0.06 g cm−3 with the OH plus O3 initiated oxidation systems and 1.38±0.03 g cm−3 with the ozonolysis dominated chemistry.

scholarly journals The effects of cloud-aerosol-interaction complexity on simulations of presummer rainfall over southern China

2019 ◽  
Author(s):  
Kalli Furtado ◽  
Paul Field ◽  
Yali Luo ◽  
Tianjun Zhou ◽  
Adrian Hill
Keyword(s):  
South China ◽  
Vertical Structure ◽  
Monsoon Rainfall ◽  
Southern China ◽  
Deep Convection ◽  
Cloud Droplets ◽  
Cloud Processing ◽  
Squall Lines ◽  
Surface Rainfall ◽  
Fully Coupled

Abstract. Convection-permitting simulations are used to understand the effects of cloud-aerosol interactions on a case of heavy rainfall over south China. The simulations are evaluated using radar observations from the South China Monsoon Rainfall Experiment and remotely sensed estimates of precipitation, clouds and radiation. We focus on the effects of complexity in cloud-aerosol interactions, especially processing and transport of dissolved material inside clouds. In particular, simulations with aerosol concentrations held constant are compared with a fully coupled cloud-aerosol-interacting system to isolate the effects of processing on a line of organised-deep convection. It is shown that in-cloud processing of aerosols can change the vertical structure of squall lines thereby inducing changes in the statistics of surface rainfall. These effects are shown to be consistent with a modulation by aerosol of the timescale of the converting cloud-droplets to rain.

scholarly journals The effects of cloud–aerosol interaction complexity on simulations of presummer rainfall over southern China

2020 ◽  
Vol 20 (8) ◽  
pp. 5093-5110
Author(s):  
Kalli Furtado ◽  
Paul Field ◽  
Yali Luo ◽  
Tianjun Zhou ◽  
Adrian Hill
Keyword(s):  
Southern China ◽  
Deep Convection ◽  
Short Wave ◽  
Wave Radiation ◽  
Cloud Droplets ◽  
Cloud Processing ◽  
Surface Rainfall ◽  
Clean Environment ◽  
Aerosol Number Concentration ◽  
Condensed Water

Abstract. Convection-permitting simulations are used to understand the effects of cloud–aerosol interactions in a case of heavy rainfall over southern China. The simulations are evaluated using radar observations from the Southern China Monsoon Rainfall Experiment (SCMREX) and remotely sensed estimates of precipitation, clouds and radiation. We focus on the effects of complexity in cloud–aerosol interactions, especially the depletion and transport of aerosol material by clouds. In particular, simulations with aerosol concentrations held constant are compared with a fully cloud–aerosol-interacting system to investigate the effects of two-way coupling between aerosols and clouds on a line of organised deep convection. It is shown that the cloud processing of aerosols can change the vertical structure of the storm by using up aerosols within the core of line, thereby maintaining a relatively clean environment which propagates with the heaviest rainfall. This induces changes in the statistics of surface rainfall, with a cleaner environment being associated with less-intense but more-frequent rainfall. These effects are shown to be related to a shortening of the timescale for converting cloud droplets to rain as the aerosol number concentration is decreased. The simulations are compared to satellite-derived estimates of surface rainfall, a condensed-water path and the outgoing flux of short-wave radiation. Simulations for fewer aerosol particles outperform the more polluted simulations for surface rainfall but give poorer representations of top-of-atmosphere (TOA) radiation.

scholarly journals Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

2017 ◽  
Author(s):  
Li-Ming Cao ◽  
Xiao-Feng Huang ◽  
Yuan-Yuan Li ◽  
Min Hu ◽  
Ling-Yan He
Keyword(s):  
Southern China ◽  
Chemical Species ◽  
Urban Atmosphere ◽  
Chemical Components ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Aerosol Pollution ◽  
Mass Spectrometer System ◽  
Spectrometer System

Abstract. Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a TD-AMS (Thermo-Denuder – Aerosol Mass Spectrometer) system was deployed to study the volatility of non-refractory PM1 species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7 ± 20.1 μg m−3, with organics being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with an MFR (mass fraction remaining) of 0.57 at 50 °C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 °C), and the volatility had a relatively linear correlation with the TD temperature (from 50 to 200 °C), with an evaporation rate of 0.45 %·°C1. Five subtypes of OA were resolved from total OAs by PMF for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass burning OA (BBOA, 8.9 %) and two oxygenated OAs (OOA): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA species presented different volatilities; the volatility sequence of OA factors at 50 °C was HOA (MFR of 0.56) > LO-OOA (0.70) > COA (0.85) ≈ BBOA (0.87) > MO-OOA (0.99). The volatility sequence of OA components suggested that HOA, rather than BBOA or COA, could be a potentially important source of LO-OOA through the oxidizing process of Evaporation – Oxidation in gas phase – Condensation. The results above can contribute to the understanding of the formation and ageing of submicron aerosols in the atmosphere and will help to constrain aerosol modelling inputs.

scholarly journals Volatility measurement of atmospheric submicron aerosols in an urban atmosphere in southern China

2018 ◽  
Vol 18 (3) ◽  
pp. 1729-1743 ◽  
Author(s):  
Li-Ming Cao ◽  
Xiao-Feng Huang ◽  
Yuan-Yuan Li ◽  
Min Hu ◽  
Ling-Yan He
Keyword(s):  
Ambient Temperature ◽  
Southern China ◽  
Chemical Species ◽  
Urban Atmosphere ◽  
Chemical Components ◽  
Formation Mechanisms ◽  
Aerosol Mass Spectrometer ◽  
Aerosol Mass ◽  
Measurement Results ◽  
High Volatility

Abstract. Aerosol pollution has been a very serious environmental problem in China for many years. The volatility of aerosols can affect the distribution of compounds in the gas and aerosol phases, the atmospheric fates of the corresponding components, and the measurement of the concentration of aerosols. Compared to the characterization of chemical composition, few studies have focused on the volatility of aerosols in China. In this study, a thermodenuder aerosol mass spectrometer (TD-AMS) system was deployed to study the volatility of non-refractory submicron particulate matter (PM1) species during winter in Shenzhen. To our knowledge, this paper is the first report of the volatilities of aerosol chemical components based on a TD-AMS system in China. The average PM1 mass concentration during the experiment was 42.7±20.1 µg m−3, with organic aerosol (OA) being the most abundant component (43.2 % of the total mass). The volatility of chemical species measured by the AMS varied, with nitrate showing the highest volatility, with a mass fraction remaining (MFR) of 0.57 at 50 ∘C. Organics showed semi-volatile characteristics (the MFR was 0.88 at 50 ∘C), and the volatility had a relatively linear correlation with the TD temperature (from the ambient temperature to 200 ∘C), with an evaporation rate of 0.45 %∘C-1. Five subtypes of OA were resolved from total OA using positive matrix factorization (PMF) for data obtained under both ambient temperature and high temperatures through the TD, including a hydrocarbon-like OA (HOA, accounting for 13.5 %), a cooking OA (COA, 20.6 %), a biomass-burning OA (BBOA, 8.9 %), and two oxygenated OAs (OOAs): a less-oxidized OOA (LO-OOA, 39.1 %) and a more-oxidized OOA (MO-OOA, 17.9 %). Different OA factors presented different volatilities, and the volatility sequence of the OA factors at 50 ∘C was HOA (MFR of 0.56) > LO-OOA (0.70) > COA (0.85) ≈ BBOA (0.87) > MO-OOA (0.99), which was not completely consistent with the sequence of their O ∕ C ratios. The high volatility of HOA implied that it had a high potential to be oxidized to secondary species in the gas phase. The aerosol volatility measurement results in this study provide useful parameters for the modeling work of aerosol evolution in China and are also helpful in understanding the formation mechanisms of secondary aerosols.

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