scholarly journals In-cloud scavenging scheme for aerosol modules

2020 ◽  
Author(s):  
Eemeli Holopainen
Keyword(s):  
Cloud Scavenging

scholarly journals The Relative Importance of Scavenging, Oxidation, and Ice-Phase Processes in the Production and Wet Deposition of Sulfate

2005 ◽  
Vol 62 (7) ◽  
pp. 2118-2135 ◽  
Author(s):  
Vlado Spiridonov ◽  
Mladjen Curic
Keyword(s):  
Wet Deposition ◽  
Lower Percentage ◽  
Relative Importance ◽  
Total Sulfur ◽  
Sulfate Production ◽  
Relative Contribution ◽  
Cloud Resolving Model ◽  
Cloud Scavenging ◽  
Nucleation Scavenging ◽  
Ice Phase

Abstract The relative importance of various processes to sulfate production and wet deposition is examined by using a cloud-resolving model coupled with a sulfate chemistry submodel. Results using different versions of the model are then compared and principal differences with respect to their dynamics, microphysics, and chemistry are carefully discussed. The results imply that the dominant microphysical and chemical conversions of sulfate in the 3D run are nucleation, scavenging, and oxidation. Due to the lower cloud water and rainwater pH, oxidation does not contribute as significantly to the sulfate mass in the 2D run as the 3D. Sensitivity tests have revealed that in-cloud scavenging in the 2D run for continental nonpolluted and continental polluted clouds accounted for 29.4% and 31.5% of the total sulfur deposited, respectively. The 3D run shows a lower percentage contribution to sulfur deposition for about 28.2% and 29.6%. In addition, subcloud scavenging for the 2D run contributed about 32.7% and 38.2%. In-cloud oxidation in the 2D run accounted for about 24.5% to 30.4% of the total sulfur mass deposited. Subcloud oxidation contributed from 21.0% to 20.6% of the total sulfur mass removed by wet deposition. In-cloud oxidation for the 3D run shows slightly lower percentage values when compared to those from the 2D run. The relative contribution of subcloud oxidation for continental nonpolluted and polluted clouds exceeds those values in the 2D run by approximately 7% and 10%, respectively. Ignoring the ice phase and considering those types of convective clouds in the 2D run may lead to a higher value of the total sulfur mass removed by the wet deposition of about 33.9% to 39.2% for the continental nonpolluted and 36.2% to 45.6% for the continental polluted distributions relative to the base runs.

scholarly journals Mercury distribution in the upper troposphere and lower most stratosphere according to measurements by the IAGOS-CARIBIC observatory, 2014–2016

2018 ◽  
Author(s):  
Franz Slemr ◽  
Andreas Weigelt ◽  
Ralf Ebinghaus ◽  
Johannes Bieser ◽  
Carl A. M. Brenninkmeijer ◽  
...  
Keyword(s):  
Large Scale ◽  
Total Mercury ◽  
Trace Gases ◽  
Boreal Winter ◽  
Signal Integration ◽  
Upper Troposphere ◽  
Cloud Scavenging ◽  
Passenger Aircraft ◽  
North And South America ◽  
North And South

Abstract. Mercury was measured onboard the IAGOS-CARIBIC passenger aircraft since May 2005 until February 2016 during nearly monthly sequences of mostly four intercontinental flights from Germany to destinations in North and South America, Africa, and South and East Asia. Most of these mercury data were obtained using an internal default signal integration procedure of the Tekran instrument but since April 2014 more precise and accurate data were obtained using post-flight manual integration of the instrument raw signal. In this paper we use the latter data. Elevated upper tropospheric total mercury (TM) concentrations due to large scale biomass burning were observed in the upper troposphere (UT) at the equator and southern latitudes during the flights to Latin America and South Africa in boreal autumn (SON) and boreal winter (DJF). TM concentrations in the lowermost stratosphere (LMS) decrease with altitude above the thermal tropopause but the gradient is less steep than reported before. Seasonal variation of the vertical TM distribution in the UT and LMS is similar to that of other trace gases with surface sources and stratospheric sinks. Using speciation experiments, we show that nearly identical TM and gaseous elementary mercury (GEM) concentrations exist at and below the tropopause. Above the thermal tropopause GEM concentrations are almost always smaller than those of TM and the TM – GEM (i.e. Hg2+) difference increases up to ~ 40 % of TM at ~ 2 km and more above the thermal tropopause. Correlations with N2O as a reference tracer suggest stratospheric lifetimes of 72 ± 37 and 74 ± 27 yr for TM and GEM, respectively, comparable to the stratospheric lifetime of COS. This coincidence, combined with pieces of evidence from us and other researchers, corroborates the hypothesis that Hg2+ formed by oxidation in the stratosphere attaches to sulfate particles formed mainly by oxidation of COS and is removed with them from the stratosphere by air mass exchange, gravitational sedimentation, and cloud scavenging processes.

scholarly journals Cloud scavenging of abundant anthropogenic refractory particles at a mountain site in North China

2018 ◽  
Author(s):  
Lei Liu ◽  
Jian Zhang ◽  
Liang Xu ◽  
Qi Yuan ◽  
Dao Huang ◽  
...  
Keyword(s):  
North China Plain ◽  
North China ◽  
Size Composition ◽  
Climate Forcing ◽  
Pollution Levels ◽  
Aerosol Cloud ◽  
The North ◽  
The North China Plain ◽  
Transmission Electron ◽  
Cloud Scavenging

Abstract. Aerosol-cloud interaction remains a major source of uncertainty in climate forcing estimate. Our knowledge about the aerosol-cloud interaction is particularly weak in heavily polluted conditions. In this study, cloud residual (cloud RES) and cloud interstitial (cloud INT) particles were collected during cloud events under different pollution levels from 22 July to 1 August, 2014 at Mt. Tai (1532 m above sea level) located in the North China Plain (NCP). Transmission electron microscopy (TEM) was used to investigate size, composition, and mixing state of individual cloud RES and INT particles. Our results show that S-rich particles were predominant (78 %) during clean periods (PM2.5 

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

2017 ◽  
Author(s):  
Guohua Zhang ◽  
Qinhao Lin ◽  
Long Peng ◽  
Xinhui Bi ◽  
Duohong Chen ◽  
...  
Keyword(s):  
Black Carbon ◽  
Single Particle ◽  
Southern China ◽  
Climate Impacts ◽  
Limited Information ◽  
Mixing State ◽  
Cloud Droplets ◽  
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 in a size range of 0.1–1.6 µm 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 internally mixed extensively with sulfate, and were activated into cloud droplets to the same extent as all the measured particles. 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 activated 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. Since limited information on BC-containing particles in the free troposphere is available, the results also provide an important reference for the representation of BC concentrations, properties, and climate impacts in modeling studies.

scholarly journals Observations on aerosol optical properties and scavenging during cloud events

2020 ◽  
Author(s):  
Antti Ruuskanen ◽  
Sami Romakkaniemi ◽  
Harri Kokkola ◽  
Antti Arola ◽  
Santtu Mikkonen ◽  
...  
Keyword(s):  
Large Scale ◽  
Aerosol Composition ◽  
Cloud Droplets ◽  
Inlet System ◽  
Scattering Coefficients ◽  
Stratus Clouds ◽  
Absorbing Material ◽  
Scattering Material ◽  
Cloud Scavenging ◽  
Increasing Temperature

Abstract. Long term statistics of atmospheric aerosol and especially cloud scavenging were studied at the Puijo measurement station in Kuopio, Finland, during October 2010–November 2014. Aerosol size distributions, scattering coefficients at three different wavelengths (450 nm, 550 nm, and 700 nm), and absorption coefficient at wavelength 637 nm were measured with a special inlet system to sample interstitial and total aerosol in clouds. On average, accumulation mode particle concentration was found to be temperature dependent with lowest average concentrations of 200 cm−3 around 0 °C increasing to more than 800 cm−3 for temperatures higher than 20 °C. From the in-cloud measurements, both scattering and absorbing material scavenging efficiencies were observed to have slightly increasing temperature dependence. At 0 °C the efficiencies of scattering and absorbing matter were 0.85 and 0.55 with slopes of 0.005 °C−1 and 0.003 °C−1, respectively. Additionally, scavenging efficiencies were studied as a function of the diameter at which half of the particles are activated into cloud droplets. This analysis indicated that the is a higher fraction of absorbing material, typically black carbon, in smaller sizes so that at least 20–30 % of interstitial particles within clouds consist of absorbing material. In addition, the PM1-inlet revealed that approximately 20 % of absorbing material was observed to reside in particles with ambient diameter larger than ~ 1 µm at relative humidity below 90 %. Similarly, 40 % of scattering material was seen to be in particles larger than 1 µm. Altogether, this dataset provides information on size dependent aerosol composition that can be applied in evaluating how well large-scale aerosol models reproduce aerosol composition, especially with respect to scavenging in stratus clouds.

scholarly journals Plant assemblages in atmospheric deposition

2019 ◽  
Author(s):  
Ke Dong ◽  
Cheolwoon Woo ◽  
Naomichi Yamamoto
Keyword(s):  
Atmospheric Deposition ◽  
Dry Deposition ◽  
Wet Deposition ◽  
High Throughput Sequencing ◽  
Sampling Site ◽  
Its2 Region ◽  
Dry And Wet Deposition ◽  
Custom Made ◽  
Plant Assemblages ◽  
Cloud Scavenging

Abstract. Plants disperse spores, pollen, and fragments into the atmosphere. The emitted plant particles return to the pedosphere by sedimentation (dry deposition) and/or by precipitation (wet deposition) and constitute part of the global cycle of substances. However, little is known regarding the taxonomic diversities and flux densities of plant particles deposited from the atmosphere. Here, plant assemblages were examined in atmospheric deposits collected in Seoul in South Korea. A custom-made automatic sampler was used to collect dry and wet deposition samples for which plant assemblages and quantities were determined using high-throughput sequencing and quantitative PCR with universal plant-specific primers targeting the internal transcribed spacer 2 (ITS2) region. Dry deposition was dominant for atmospheric deposition of plant particles (87 %). The remaining 13 % was deposited by precipitation, i.e., wet deposition, via rainout (in-cloud scavenging) and/or washout (below-cloud scavenging). Plant assemblage structures did not differ significantly between dry and wet deposition, indicating that washout, which is likely taxon-independent, predominated rainout, which is likely taxon-dependent, for wet deposition of atmospheric plant particles. A small number of plant genera were detected only in wet deposition, indicating that they might be specifically involved in precipitation through acting as nucleation sites in the atmosphere. Future interannual monitoring will control for the seasonality of atmospheric plant assemblages observed at our sampling site. Future global monitoring is also proposed to investigate geographical differences and investigate whether endemic species are involved in plant-mediated bioprecipitation in regional ecological systems.

Stage-resolved in-cloud scavenging of submicron and BC-containing particles: A case study

2021 ◽  
Vol 244 ◽  
pp. 117883
Author(s):  
Yuxiang Yang ◽  
Qinhao Lin ◽  
Yuzhen Fu ◽  
Xiufeng Lian ◽  
Feng Jiang ◽  
...  
Keyword(s):  
Cloud Scavenging

scholarly journals Characterising mass-resolved mixing state of black carbon in Beijing using a morphology-independent measurement method

2020 ◽  
Vol 20 (6) ◽  
pp. 3645-3661 ◽  
Author(s):  
Chenjie Yu ◽  
Dantong Liu ◽  
Kurtis Broda ◽  
Rutambhara Joshi ◽  
Jason Olfert ◽  
...  
Keyword(s):  
Black Carbon ◽  
Atmospheric Aerosols ◽  
Particle Morphology ◽  
Urban Site ◽  
Inversion Method ◽  
Mixing State ◽  
State Index ◽  
Cloud Scavenging ◽  
Highly Correlated ◽  
State Mixing

Abstract. Refractory black carbon (rBC) in the atmosphere is known for its significant impacts on climate. The relationship between the microphysical and optical properties of rBC remains poorly understood and is influenced by its size and mixing state. Mixing state also influences its cloud scavenging potential and thus atmospheric lifetime. This study presents a coupling of a centrifugal particle mass analyser (CPMA) and a single-particle soot photometer (SP2) for the morphology-independent quantification of the mixing state of rBC-containing particles, used in the urban site of Beijing as part of the Air Pollution and Human Health–Beijing (APHH-Beijing) project during winter (10 November–10 December 2016) and summer (18 May–25 June 2017). This represents a highly dynamic polluted environment with a wide variety of conditions that could be considered representative of megacity area sources in Asia. An inversion method (used for the first time on atmospheric aerosols) is applied to the measurements to present two-variable distributions of both rBC mass and total mass of rBC-containing particles and calculate the mass-resolved mixing state of rBC-containing particles, using previously published metrics. The mass ratio between non-rBC material and rBC material (MR) is calculated to determine the thickness of a hypothetical coating if the rBC and other material followed a concentric sphere model (the equivalent coating thickness). The bulk MR (MRbulk) was found to vary between 2 and 12 in winter and between 2 and 3 in summer. This mass-resolved mixing state is used to derive the mass-weighted mixing state index for the rBC-containing particles (χrBC). χrBC quantifies how uniformly the non-rBC material is distributed across the rBC-containing-particle population, with 100 % representing uniform mixing. The χrBC in Beijing varied between 55 % and 70 % in winter depending on the dominant air masses, and χrBC was highly correlated with increased MRbulk and PM1 mass concentration in winter, whereas χrBC in summer varied significantly (ranging 60 %–75 %) within the narrowly distributed MRbulk and was found to be independent of air mass sources. In some model treatments, it is assumed that more atmospheric ageing causes the BC to tend towards a more homogeneous mixture, but this leads to the conclusion that the MRbulk may only act as a predictor of χrBC in winter. The particle morphology-independent and mass-based information on BC mixing used in this and future studies can be applied to mixing-state-aware models investigating atmospheric rBC ageing.

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