scholarly journals Compositions and mixing states of aerosol particles by aircraft observations in the Arctic springtime, 2018

2020 ◽  
Author(s):  
Kouji Adachi ◽  
Naga Oshima ◽  
Sho Ohata ◽  
Atsushi Yoshida ◽  
Nobuhiro Moteki ◽  
...  
Keyword(s):  
Climate Model ◽  
Mineral Dust ◽  
Model Simulation ◽  
Aerosol Particles ◽  
Sea Salt ◽  
The Arctic ◽  
Radiation Balance ◽  
Mixing State ◽  
Carbonaceous Particles ◽  
Airborne Measurements

Abstract. Aerosol particles were collected at various altitudes in the Arctic during the Polar Airborne Measurements and Arctic Regional Climate Model Simulation Project (PAMARCMiP 2018) conducted in the early spring of 2018. The composition, size, number fraction, and mixing state of individual aerosol particles were analyzed using transmission electron microscopy (TEM), and their sources and transport were evaluated by numerical model simulations. We found that sulfate, sea-salt, mineral-dust, K-bearing, and carbonaceous particles were the major aerosol constituents and were internally mixed. The number fraction of mineral-dust and sea-salt particles decreased with increasing altitude. The K-bearing particles increased within a biomass burning (BB) plume at altitudes > 3900 m, which originated from Siberia. Chlorine in sea-salt particles was replaced with sulfate at high altitudes. These results suggest that the sources, transport, and aging of Arctic aerosols largely vary depending on the altitude and airmass history. We also provide the occurrences of solid-particle inclusions (soot, fly-ash, and Fe-aggregate particles), some of which are light-absorbing and potential ice-nucleating particles. Our TEM measurements revealed, for the first time, the detailed mixing state of individual particles at various altitudes in the Arctic. This information facilitates the accurate evaluation of the aerosol influences on Arctic haze, radiation balance, cloud formation, and snow/ice albedo when deposited.

scholarly journals Compositions and mixing states of aerosol particles by aircraft observations in the Arctic springtime, 2018

2021 ◽  
Vol 21 (5) ◽  
pp. 3607-3626
Author(s):  
Kouji Adachi ◽  
Naga Oshima ◽  
Sho Ohata ◽  
Atsushi Yoshida ◽  
Nobuhiro Moteki ◽  
...  
Keyword(s):  
Biomass Burning ◽  
Mineral Dust ◽  
Model Simulation ◽  
Aerosol Particles ◽  
Sea Salt ◽  
The Arctic ◽  
Radiation Balance ◽  
Mixing State ◽  
Carbonaceous Particles ◽  
Airborne Measurements

Abstract. Aerosol particles were collected at various altitudes in the Arctic during the Polar Airborne Measurements and Arctic Regional Climate Model Simulation Project 2018 (PAMARCMiP 2018) conducted in the early spring of 2018. The composition, size, number fraction, and mixing state of individual aerosol particles were analyzed using transmission electron microscopy (TEM), and their sources and transport were evaluated by numerical model simulations. We found that sulfate, sea-salt, mineral-dust, K-bearing, and carbonaceous particles were the major aerosol constituents. Many particles were composed of two or more compositions that had coagulated and were coated with sulfate, organic materials, or both. The number fraction of mineral-dust and sea-salt particles decreased with increasing altitude. The K-bearing particles increased within a biomass burning (BB) plume at altitudes > 3900 m, which originated from Siberia. Chlorine in sea-salt particles was replaced with sulfate at high altitudes. These results suggest that the sources, transport, and aging of Arctic aerosols largely vary depending on the altitude and air-mass history. We also provide the occurrences of solid-particle inclusions (soot, fly-ash, and Fe-aggregate particles), some of which are light-absorbing particles. They were mainly emitted from anthropogenic and biomass burning sources and were embedded within other relatively large host particles. Our TEM measurements revealed the detailed mixing state of individual particles at various altitudes in the Arctic. This information facilitates the accurate evaluation of the aerosol influences on Arctic haze, radiation balance, cloud formation, and snow/ice albedo when deposited.

scholarly journals Mixing states of Amazon-basin aerosol particles transported over long distances using transmission electron microscopy

2020 ◽  
Author(s):  
Kouji Adachi ◽  
Naga Oshima ◽  
Zhaoheng Gong ◽  
Suzane de Sá ◽  
Adam P. Bateman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Amazon Basin ◽  
Mineral Dust ◽  
Aerosol Particles ◽  
Sea Salt ◽  
Anthropogenic Sources ◽  
Natural Sources ◽  
Transmission Electron ◽  
Mixing States

Abstract. The Amazon basin is important for understanding the global climate both because of its carbon cycle and as a laboratory for obtaining basic knowledge of the continental background atmosphere. Aerosol particles play an important role in the climate and weather, and knowledge of their compositions and mixing states is necessary to understand their influence on the climate. For this study, we collected aerosol particles from the Amazon basin during the Green Ocean Amazon (GoAmazon2014/5) campaign (February to March 2014) at the T3 site, which locates about 70 km from Manaus, and analyzed using transmission electron microscopy (TEM). TEM has better spatial resolution than other instruments, which enables us to analyse the occurrences of components that attach to or are embedded within other particles. Based on the TEM results of more than 10,000 particles from several transport events, this study shows the occurrences of individual particles including compositions, size distributions, number fractions, and possible sources of materials that mix with other particles. Aerosol particles during the wet season were from both natural sources such as the Amazon forest, Saharan desert, Atlantic Ocean, and African biomass burning and anthropogenic sources such as Manaus and local emissions. These particles mix together at an individual particle scale. The number fractions of mineral dust and sea-salt particles increased almost three-fold when long-range transport (LRT) from the African continent occurred. Nearly 20 % of mineral dust and primary biological aerosol particles attached sea salts on their surfaces. Sulfates were also internally mixed with sea-salt and mineral dust particles. The TEM element mapping images showed that several components with sizes of hundreds of nanometres from different sources commonly occur within individual LRT aerosol particles. We conclude that many aerosol particles from natural sources change their compositions by mixing during transport. The compositions and mixing states of these particles after emission result in changes in their hygroscopic and optical properties and should be considered when assessing their effects on climate.

Rapid neoglaciation on Ellesmere Island promoted by enhanced summer snowfall in a transient climate model simulation of the middle-late-Holocene

The Holocene ◽  
2020 ◽  
Vol 30 (10) ◽  
pp. 1474-1480
Author(s):  
Stephen J Vavrus ◽  
Feng He ◽  
John E Kutzbach ◽  
William F Ruddiman
Keyword(s):  
Snow Depth ◽  
Late Holocene ◽  
Climate Model ◽  
Model Simulation ◽  
Short Circuit ◽  
Ellesmere Island ◽  
The Arctic ◽  
Holocene Thermal Maximum ◽  
Model Driven ◽  
The Arctic Oscillation

Arctic neoglaciation following the Holocene Thermal Maximum is an important feature of late-Holocene climate. We investigated this phenomenon using a transient 6000-year simulation with the CESM-CAM5 climate model driven by orbital forcing, greenhouse gas concentrations, and a land use reconstruction. During the first three millennia analyzed here (6–3 ka), mean Arctic snow depth increases, despite enhanced greenhouse forcing. Superimposed on this secular trend is a very abrupt increase in snow depth between 5 and 4.9 ka on Ellesmere Island and the Greenland coasts, in rough agreement with the timing of observed neoglaciation in the region. This transition is especially extreme on Ellesmere Island, where end-of-summer snow coverage jumps from nearly 0 to virtually 100% in 1 year, and snow depth increases to the model’s imposed maximum within 15 years. This climatic shift involves more than the Milankovitch-based expectation of cooler summers causing less snow melt. Coincident with the onset of the cold regime are two consecutive summers with heavy snowfall on Ellesmere Island that help to short-circuit the normal seasonal melt cycle. These heavy snow seasons are caused by synoptic-scale, cyclonic circulation anomalies over the Arctic Ocean and Canadian Archipelago, including an extremely positive phase of the Arctic Oscillation. Our study reveals that a climate model can produce sudden climatic transitions in this region prone to glacial inception and exceptional variability, due to a dynamic mechanism (more summer snowfall induced by an extreme circulation anomaly) that augments the traditional Milankovitch thermodynamic explanation of orbitally induced glacier development.

scholarly journals Organic coating on sulfate and soot particles during late summer in the Svalbard Archipelago

2019 ◽  
Vol 19 (15) ◽  
pp. 10433-10446 ◽  
Author(s):  
Hua Yu ◽  
Weijun Li ◽  
Yangmei Zhang ◽  
Peter Tunved ◽  
Manuel Dall'Osto ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Optical Properties ◽  
Secondary Ion Mass Spectrometry ◽  
Late Summer ◽  
Organic Coating ◽  
The Arctic ◽  
Mixing State ◽  
Particle Volume ◽  
Svalbard Archipelago ◽  
Carbonaceous Particles

Abstract. Interaction of anthropogenic particles with radiation and clouds plays an important role in Arctic climate change. The mixing state of aerosols is a key parameter to influence aerosol radiation and aerosol–cloud interactions. However, little is known of this parameter in the Arctic, preventing an accurate representation of this information in global models. Here we used transmission electron microscopy with energy-dispersive X-ray spectrometry, scanning electron microscopy, nanoscale secondary ion mass spectrometry, and atomic forces microscopy to determine the size and mixing state of individual sulfate and carbonaceous particles at 100 nm to 2 µm collected in the Svalbard Archipelago in summer. We found that 74 % by number of non-sea-salt sulfate particles were coated with organic matter (OM); 20 % of sulfate particles also had soot inclusions which only appeared in the OM coating. The OM coating is estimated to contribute 63 % of the particle volume on average. To understand how OM coating influences optical properties of sulfate particles, a Mie core–shell model was applied to calculate optical properties of individual sulfate particles. Our result shows that the absorption cross section of individual OM-coated particles significantly increased when assuming the OM coating as light-absorbing brown carbon. Microscopic observations here suggest that OM modulates the mixing structure of fine Arctic sulfate particles, which may determine their hygroscopicity and optical properties.

scholarly journals Characterisation of individual aerosol particles collected during a haze episode in Incheon, Korea using the quantitative ED-EPMA technique

2011 ◽  
Vol 11 (3) ◽  
pp. 1327-1337 ◽  
Author(s):  
H. Geng ◽  
J. Y. Ryu ◽  
S. Maskey ◽  
H.-J. Jung ◽  
C.-U. Ro
Keyword(s):  
Mineral Dust ◽  
Aerosol Particles ◽  
Relative Number ◽  
Sea Salt ◽  
Motor Vehicles ◽  
Dust Particles ◽  
Formation Mechanisms ◽  
X Ray ◽  
Haze Episode ◽  
Haze Days

Abstract. A quantitative energy-dispersive electron probe X-ray microanalysis (ED-EPMA), called low-Z particle EPMA, was used to analyse individual aerosol particles collected in Incheon, Korea on 13–18 October 2008 (a typical haze episode occurred from 15 to 18 October). Overall 3600 individual particles in PM2.5-10 and PM1.0-2.5 fractions from 12 aerosol samples collected on haze and non-haze days were analysed. The analysed particles were classified, based on their X-ray spectral data together with their secondary electron images. The major particle types included organic carbon (OC), elemental carbon (EC), sea-salt, mineral dust (such as aluminosilicate, SiO2, CaCO3/CaMgCO3, etc.), (NH4)2SO4/NH4HSO4-containing, K-containing, Fe-rich and fly ash particles. Their relative number abundance results showed that OC particles were significantly increased while sea-salts and mineral dust particles were significantly decreased (especially in PM1.0-2.5 fraction) when haze occurred. For the other particle types (except Fe-rich particles in PM2.5-10 fraction), there were no significant differences in their relative abundances between haze and non-haze samples. On non-haze days, the nitrate-containing reacted sea-salt and mineral dust particles in PM1.0-2.5 fraction significantly outnumbered the sulfate-containing ones, whereas it was the reverse on haze days, implying that on haze days there were special sources or formation mechanisms for fine aerosol particles (≤2.5 μm in aerodynamic diameter). The emission of air pollutants from motor vehicles and stagnant meteorological conditions, such as low wind speed and high relative humidity, might be responsible for the elevated level of OC particles on haze days.

scholarly journals Depositional ice nucleation onto hydrated NaCl particles: a new mechanism for ice formation in the troposphere

2011 ◽  
Vol 11 (8) ◽  
pp. 23139-23167 ◽  
Author(s):  
M. E. Wise ◽  
K. J. Baustian ◽  
T. Koop ◽  
M. A. Freedman ◽  
E. J. Jensen ◽  
...  
Keyword(s):  
Marine Boundary Layer ◽  
Aerosol Particles ◽  
Ice Nucleation ◽  
Sea Salt ◽  
Ice Formation ◽  
Radiation Balance ◽  
Atmospheric Conditions ◽  
Hydrated Form ◽  
Sea Salt Aerosol ◽  
Ice Nuclei

Abstract. Sea-salt aerosol particles (SSA) are ubiquitous in the marine boundary layer and over coastal areas. Therefore SSA have ability to directly and indirectly affect the Earth's radiation balance. The influence SSA have on climate is related to their water uptake and ice nucleation characteristics. In this study, optical microscopy coupled with Raman spectroscopy was used to detect the formation of an NaCl hydrate that could form under atmospheric conditions. NaCl(s) particles deliquesced at the well established value of 75.7 ± 2.5 % RH. NaCl(aq) particles effloresced to a mixture of hydrated and non-hydrated particles at temperatures between 236 and 252 K. The aqueous particles effloresced into the non-hydrated form at temperatures warmer than 252 K. At temperatures colder than 236 K all particles effloresced into the hydrated form. The deliquescence relative humidities (DRH) of hydrated NaCl(s) particles ranged from 76.6 to 93.2 % RH. Based on the measured DRH and efflorescence relative humidities (ERH), we estimate crystalline NaCl particles could be in the hydrated form 40–80 % of the time in the troposphere. Additionally, the ice nucleating abilities of NaCl(s) and hydrated NaCl(s) were determined at temperatures ranging from 221 to 238 K. NaCl(s) particles depositionally nucleated ice at an average Sice value of 1.11 ± 0.07. Hydrated NaCl(s) particles depositionally nucleated ice at an average Sice value of 1.02 ± 0.04. When a mixture of hydrated and anhydrous NaCl(s) particles was present in the same sample, ice preferentially nucleated on the hydrated particles 100 % of the time. While both types of particles are efficient ice nuclei, hydrated NaCl(s) particles are better ice nuclei than NaCl(s) particles.

scholarly journals Accommodation coefficient of HOBr on deliquescent sodium bromide aerosol particles

2002 ◽  
Vol 2 (1) ◽  
pp. 1-28 ◽  
Author(s):  
M. Wachsmuth ◽  
H. W. Gäggeler ◽  
R. von Glasow ◽  
M. Ammann
Keyword(s):  
Ozone Depletion ◽  
Aerosol Particles ◽  
Accommodation Coefficient ◽  
Sea Salt ◽  
Sodium Bromide ◽  
Radioactive Isotopes ◽  
The Arctic ◽  
Sea Salt Aerosol ◽  
Mass Accommodation Coefficient ◽  
Salt Brine

Abstract. Uptake of HOBr on sea salt aerosol, sea salt brine or ice is believed to be a key process providing a source of photolabile bromine (Br2) and sustaining ozone depletion cycles in the arctic troposphere. In the present study, uptake of HOBr on sodium bromide (NaBr) aerosol particles was investigated at an extremely low HOBr concentration of 300 cm-3 using the short-lived radioactive isotopes 83-86Br. Under these conditions, at maximum one HOBr molecule was taken up per particle. The rate of uptake was clearly limited by the mass accommodation coefficient, which was calculated to be 0.6±0.2. This value is a factor of 10 larger than estimates used in earlier models. The atmospheric implications are discussed using the box model "MOCCA'', showing that the increase of the accommodation coefficient of HOBr by a factor of 10 only slightly affects net ozone loss, but significantly increases chlorine release.

scholarly journals The global aerosol–climate model ECHAM6.3–HAM2.3 – Part 1: Aerosol evaluation

2019 ◽  
Vol 12 (4) ◽  
pp. 1643-1677 ◽  
Author(s):  
Ina Tegen ◽  
David Neubauer ◽  
Sylvaine Ferrachat ◽  
Colombe Siegenthaler-Le Drian ◽  
Isabelle Bey ◽  
...  
Keyword(s):  
Climate Model ◽  
Mineral Dust ◽  
Sea Salt ◽  
Carbonaceous Aerosol ◽  
Anthropogenic Aerosol ◽  
Aerosol Model ◽  
Online Computation ◽  
Climate Interactions ◽  
Cloud Activation ◽  
Aerosol Emissions

Abstract. We introduce and evaluate aerosol simulations with the global aerosol–climate model ECHAM6.3–HAM2.3, which is the aerosol component of the fully coupled aerosol–chemistry–climate model ECHAM–HAMMOZ. Both the host atmospheric climate model ECHAM6.3 and the aerosol model HAM2.3 were updated from previous versions. The updated version of the HAM aerosol model contains improved parameterizations of aerosol processes such as cloud activation, as well as updated emission fields for anthropogenic aerosol species and modifications in the online computation of sea salt and mineral dust aerosol emissions. Aerosol results from nudged and free-running simulations for the 10-year period 2003 to 2012 are compared to various measurements of aerosol properties. While there are regional deviations between the model and observations, the model performs well overall in terms of aerosol optical thickness, but may underestimate coarse-mode aerosol concentrations to some extent so that the modeled particles are smaller than indicated by the observations. Sulfate aerosol measurements in the US and Europe are reproduced well by the model, while carbonaceous aerosol species are biased low. Both mineral dust and sea salt aerosol concentrations are improved compared to previous versions of ECHAM–HAM. The evaluation of the simulated aerosol distributions serves as a basis for the suitability of the model for simulating aerosol–climate interactions in a changing climate.

scholarly journals A comprehensive study of hygroscopic properties of calcium- and magnesium-containing salts: implication for hygroscopicity of mineral dust and sea salt aerosols

2019 ◽  
Vol 19 (4) ◽  
pp. 2115-2133 ◽  
Author(s):  
Liya Guo ◽  
Wenjun Gu ◽  
Chao Peng ◽  
Weigang Wang ◽  
Yong Jie Li ◽  
...  
Keyword(s):  
Growth Factors ◽  
Physicochemical Properties ◽  
Mineral Dust ◽  
Aerosol Particles ◽  
Sea Salt ◽  
Hygroscopic Growth ◽  
Continuous Growth ◽  
Sea Salt Aerosols ◽  
Hygroscopic Properties ◽  
Calcium And Magnesium

Abstract. Calcium- and magnesium-containing salts are important components for mineral dust and sea salt aerosols, but their physicochemical properties are not well understood yet. In this study, hygroscopic properties of eight Ca- and Mg-containing salts, including Ca(NO3)2⚫4H2O, Mg(NO3)2⚫6H2O, MgCl2⚫6H2O, CaCl2⚫6H2O, Ca(HCOO)2, Mg(HCOO)2⚫2H2O, Ca(CH3COO)2⚫H2O and Mg(CH3COO)2⚫4H2O, were investigated using two complementary techniques. A vapor sorption analyzer was used to measure the change of sample mass with relative humidity (RH) under isotherm conditions, and the deliquescence relative humidities (DRHs) for temperature in the range of 5–30 ∘C as well as water-to-solute ratios as a function of RH at 5 and 25 ∘C were reported for these eight compounds. DRH values showed large variation for these compounds; for example, at 25 ∘C DRHs were measured to be ∼ 28.5 % for CaCl2⚫6H2O and >95 % for Ca(HCOO)2 and Mg(HCOO)2⚫2H2O. We further found that the dependence of DRH on temperature can be approximated by the Clausius–Clapeyron equation. In addition, a humidity tandem differential mobility analyzer was used to measure the change in mobility diameter with RH (up to 90 %) at room temperature, in order to determine hygroscopic growth factors of aerosol particles generated by atomizing water solutions of these eight compounds. All the aerosol particles studied in this work, very likely to be amorphous under dry conditions, started to grow at very low RH (as low as 10 %) and showed continuous growth with RH. Hygroscopic growth factors at 90 % RH were found to range from 1.26 ± 0.04 for Ca(HCOO)2 to 1.79 ± 0.03 for Ca(NO3)2, and the single hygroscopicity parameter ranged from 0.09–0.13 for Ca(CH3COO)2 to 0.49–0.56 for Ca(NO3)2. Overall, our work provides a comprehensive investigation of hygroscopic properties of these Ca- and Mg-containing salts, largely improving our knowledge of the physicochemical properties of mineral dust and sea salt aerosols.

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