Aerosol distribution around Svalbard during intense easterly winds

Abstract. This paper reports on backscatter and depolarization measurements by an airborne lidar in the Arctic during the ASTAR 2004 campaign. A unique weather situation facilitated the observation of the aerosol concentration under strongly forced atmospheric conditions. The vigorous easterly winds distorted the flow past Svalbard in such a way that unique mesoscale features were visible in the remote-sensing observations. Mesoscale numerical modelling was applied to identify the sources of the aerosol plumes and to explain the observed patterns.

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Dry versus wet marine particle optical properties: RH dependence of depolarization ratio, backscatter, and extinction from multiwavelength lidar measurements during SALTRACE

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-14199-2017 ◽

2017 ◽

Vol 17 (23) ◽

pp. 14199-14217 ◽

Cited By ~ 35

Author(s):

Moritz Haarig ◽

Albert Ansmann ◽

Josef Gasteiger ◽

Konrad Kandler ◽

Dietrich Althausen ◽

...

Keyword(s):

Sea Salt ◽

Strong Increase ◽

Aerosol Layer ◽

Marine Aerosol ◽

Depolarization Ratio ◽

Atmospheric Conditions ◽

Hygroscopic Growth ◽

Backscatter Coefficient ◽

Linear Depolarization Ratio ◽

Lidar Observations

Abstract. Triple-wavelength lidar observations of the depolarization ratio and the backscatter coefficient of marine aerosol as a function of relative humidity (RH) are presented with a 5 min time resolution. The measurements were performed at Barbados (13° N, 59° W) during the Saharan Aerosol Long-range Transport and Aerosol-Cloud interaction Experiment (SALTRACE) winter campaign in February 2014. The phase transition from spherical sea salt particles to cubic-like sea salt crystals was observed with a polarization lidar. The radiosonde and water-vapor Raman lidar observations show a drop in RH below 50 % in the marine aerosol layer simultaneously with a strong increase in particle linear depolarization ratio, which reaches values up to 0.12 ± 0.08 (at 355 nm), 0.15 ± 0.03 (at 532 nm), and 0.10 ± 0.01 (at 1064 nm). The lidar ratio (extinction-to-backscatter ratio) increased from 19 and 23 sr for spherical sea salt particles to 27 and 25 sr (at 355 and 532 nm, respectively) for cubic-like particle ensembles. Furthermore the scattering enhancement due to hygroscopic growth of the marine aerosol particles under atmospheric conditions was measured. Extinction enhancement factors from 40 to 80 % RH of 1.94 ± 0.94 at 355 nm, 3.70 ± 1.14 at 532 nm, and 5.37 ± 1.66 at 1064 nm were found. The enhanced depolarization ratios and lidar ratios were compared to modeling studies of cubic sea salt particles.

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Sea salt aerosols as a reactive surface for inorganic and organic acidic gases in the Arctic troposphere

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-11341-2015 ◽

2015 ◽

Vol 15 (19) ◽

pp. 11341-11353 ◽

Cited By ~ 37

Author(s):

J. W. Chi ◽

W. J. Li ◽

D. Z. Zhang ◽

J. C. Zhang ◽

Y. T. Lin ◽

...

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Sea Salt ◽

The Arctic ◽

Amorphous Coating ◽

Acidic Gases ◽

Sea Salt Aerosols ◽

New Findings ◽

Arctic Atmosphere ◽

Inorganic And Organic

Abstract. Sea salt aerosols (SSA) are dominant particles in the Arctic atmosphere and determine the polar radiative balance. SSA react with acidic pollutants that lead to changes in physical and chemical properties of their surface, which in turn alter their hygroscopic and optical properties. Transmission electron microscopy with energy-dispersive X-ray spectrometry was used to analyze morphology, composition, size, and mixing state of individual SSA at Ny-Ålesund, Svalbard, in summertime. Individual fresh SSA contained cubic NaCl coated by certain amounts of MgCl2 and CaSO4. Individual partially aged SSA contained irregular NaCl coated by a mixture of NaNO3, Na2SO4, Mg(NO3)2, and MgSO4. The comparison suggests the hydrophilic MgCl2 coating in fresh SSA likely intrigued the heterogeneous reactions at the beginning of SSA and acidic gases. Individual fully aged SSA normally had Na2SO4 cores and an amorphous coating of NaNO3. Elemental mappings of individual SSA particles revealed that as the particles ageing Cl gradually decreased, the C, N, O, and S content increased. 12C- mapping from nanoscale secondary ion mass spectrometry indicates that organic matter increased in the aged SSA compared with the fresh SSA. 12C- line scan further shows that organic matter was mainly concentrated on the aged SSA surface. These new findings indicate that this mixture of organic matter and NaNO3 on particle surfaces likely determines their hygroscopic and optical properties. These abundant SSA as reactive surfaces adsorbing inorganic and organic acidic gases can shorten acidic gas lifetime and influence the possible gaseous reactions in the Arctic atmosphere, which need to be incorporated into atmospheric chemical models in the Arctic troposphere.

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Lidar characterization of the Arctic atmosphere during ASTAR 2007: four cases studies of boundary layer, mixed-phase and multi-layer clouds

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-2847-2010 ◽

2010 ◽

Vol 10 (6) ◽

pp. 2847-2866 ◽

Cited By ~ 9

Author(s):

A. Lampert ◽

C. Ritter ◽

A. Hoffmann ◽

J.-F. Gayet ◽

G. Mioche ◽

...

Keyword(s):

Boundary Layer ◽

Case Studies ◽

Airborne Lidar ◽

Mixed Phase ◽

Spherical Particles ◽

The Arctic ◽

Free Troposphere ◽

Atmospheric Conditions ◽

Raman Lidar ◽

Tropospheric Aerosol

Abstract. During the Arctic Study of Tropospheric Aerosol, Clouds and Radiation (ASTAR), which was conducted in Svalbard in March and April 2007, tropospheric Arctic clouds were observed with two ground-based backscatter lidar systems (micro pulse lidar and Raman lidar) and with an airborne elastic lidar. In the time period of the ASTAR 2007 campaign, an increase in low-level cloud cover (cloud tops below 2.5 km) from 51% to 65% was observed above Ny-Ålesund. Four different case studies of lidar cloud observations are analyzed: With the ground-based Raman lidar, a layer of spherical particles was observed at an altitude of 2 km after the dissolution of a cloud. The layer probably consisted of small hydrated aerosol (radius of 280 nm) with a high number concentration (around 300 cm−3) at low temperatures (−30 °C). Observations of a boundary layer mixed-phase cloud by airborne lidar and concurrent airborne in situ and spectral solar radiation sensors revealed the localized process of total glaciation at the boundary of different air masses. In the free troposphere, a cloud composed of various ice layers with very different optical properties was detected by the Raman lidar, suggesting large differences of ice crystal size, shape and habit. Further, a mixed-phase double layer cloud was observed by airborne lidar in the free troposphere. Local orography influenced the evolution of this cloud. The four case studies revealed relations of cloud properties and specific atmospheric conditions, which we plan to use as the base for numerical simulations of these clouds.

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Sea salt aerosols as a reactive surface for inorganic and organic acidic gases in the arctic troposphere

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-15-16715-2015 ◽

2015 ◽

Vol 15 (12) ◽

pp. 16715-16745 ◽

Cited By ~ 3

Author(s):

J. W. Chi ◽

W. J. Li ◽

D. Z. Zhang ◽

J. C. Zhang ◽

Y. T. Lin ◽

...

Keyword(s):

Organic Matter ◽

Optical Properties ◽

Sea Salt ◽

Heterogeneous Reactions ◽

The Arctic ◽

Amorphous Coating ◽

Acidic Gases ◽

Sea Salt Aerosols ◽

New Findings ◽

Inorganic And Organic

Abstract. Sea salt aerosols (SSA) are dominant particles in the arctic atmosphere and determine the polar radiative balance. SSA react with acidic pollutants that lead to changes of physical and chemical properties of their surface, which in turn alter their hygroscopic and optical properties. Transmission electron microscopy with energy-dispersive X-ray spectrometry was used to analyze morphology, composition, size, and mixing state of individual SSA at Ny-Ålesund, Svalbard in summertime. Individual fresh SSA contained cubic NaCl coated by certain amounts of MgCl2 and CaSO4. Individual partially aged SSA contained irregular NaCl coated by a mixture of NaNO3, Na2SO4, Mg(NO3)2, and MgSO4. The comparison suggests the hydrophilic MgCl2 coating in fresh SSA likely intrigued the heterogeneous reactions at the beginning of SSA and acidic gases. Individual fully aged SSA normally had Na2SO4 cores and an amorphous coating of NaNO3. Elemental mappings of individual SSA particles revealed that as the particles ageing Cl gradually decreased but the C, N, O, and S content increased. 12C14N− mapping from nanoscale secondary ion mass spectrometry indicates that organic matter increased in the aged SSA compared with the fresh SSA. 12C14N− line scans further show that organic matter was mainly concentrated on the aged SSA surface. These new findings indicate that this mixture of organic matter and NaNO3 on particle surfaces determines their hygroscopic and optical properties. These abundant SSA, whose reactive surfaces absorb inorganic and organic acidic gases in the arctic troposphere, need to be incorporated into atmospheric chemical models.

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Experimental and theoretical study on the capture/desorption of gaseous methyl iodide on sea salt aerosols

10.5194/egusphere-egu2020-11132 ◽

2020 ◽

Author(s):

Céline Toubin ◽

Hanaa Houjeij ◽

Maxime Infuso ◽

Gregoire Anne-Cécile ◽

Le Bourdon Gwenaelle ◽

...

Keyword(s):

Methyl Iodide ◽

Theoretical Calculations ◽

Particle Surface ◽

Sea Salt ◽

Ab Initio Molecular Dynamics ◽

Atmospheric Conditions ◽

Absorption Bands ◽

Experimental Conditions ◽

Development Fund ◽

Sea Salt Aerosols

Iodine-131, when released into the environment during severe nuclear power plant accident can have a high radiological impact on the population at short term [1]. Interaction between gaseous Iodine compounds and aerosols was not considered by the current post-accident management. In this context, this work was focused on investigating the influence of sea salt aerosols on the transport of gaseous methyl iodide (CH3I). The identification of uptake processes as well as the formation of new products at the particle surfaces was the main objectives.We have studied the interaction between NaCl particles as surrogate of sea salt particles and CH3I in various humidity conditions to reproduce the atmospheric conditions.The nature of this interaction was investigated by Infrared Spectroscopy (DRIFTS, Diffuse Reflectance Infrared Fourier Spectroscopy). Solid NaCl was exposed to CH3I (1000 and 500 ppm) with a relative humidity (RH) ranging between 0 and 80%.DRIFTS results clearly evidenced adsorbed CH3I on NaCl particles surface under both dry and humid conditions. The adsorption process can be fitted with First-order Langmuir adsorption isotherm model and exhibited very low uptake coefficients in all the experimental conditions.Additionally, to the CH3I absorption bands, the DRIFT spectrum evidenced typical absorption bands that could be assigned either to the CH2 deformation of CH2I2 or to CH3 degenerate rocking of CH3Cl. The formation of new bands appears only when CH3I is in presence of halogenated salts. However, at RH = 80%, the water layer at the particle surface inhibits the interaction between gaseous CH3I and NaCl surface due to the low solubility of CH3I in water.Theoretical calculations are carried out to complement the experimental results. Isolated hydrated clusters of CH3I are characterized by means of electronic structure calculations and ab initio molecular dynamics is used to mimic the CH3I / salt system at various humidities.Although the uptake and accommodation coefficients of CH3I are quite low, a coverage of particle surface with CH3I-derived compounds may affect the reactivity of the particles and in term the cycling life of Iodine in the atmosphere.Reference[1] Lebel, L. S.; Dickson, R. S.; Glowa, G. A. J. Environ. Radioact. 2016, 151, 82&#8211;93.We acknowledge support by the French government through the Program &#8220;Investissement d'avenir&#8221; through the Labex CaPPA (contract ANR-11-LABX-0005-01) and I-SITE ULNE project OVERSEE (contract ANR-16-IDEX-0004), CPER CLIMIBIO (European Regional Development Fund, Hauts de France council, French Ministry of Higher Education and Research) and French national supercomputing facilities (grants DARI x2016081859 and A0050801859).

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Dry versus wet marine particle optical properties: RH dependence of depolarization ratio, backscatter and extinction from multiwavelength lidar measurements during SALTRACE

10.5194/acp-2017-545 ◽

2017 ◽

Cited By ~ 1

Author(s):

Moritz Haarig ◽

Albert Ansmann ◽

Josef Gasteiger ◽

Konrad Kandler ◽

Dietrich Althausen ◽

...

Keyword(s):

Relative Humidity ◽

Sea Salt ◽

Strong Increase ◽

Aerosol Layer ◽

Marine Aerosol ◽

Depolarization Ratio ◽

Atmospheric Conditions ◽

Backscatter Coefficient ◽

Lidar Observations ◽

532 Nm

Abstract. Three-wavelength lidar observations of the depolarization ratio and the backscatter coefficient of marine aerosol as a function of relative humidity (RH) are presented. The humidity dependence of the extinction coefficient and the shape dependence of the lidar ratio were observed in the UV and visible. The phase transition from spherical sea salt particles to cubic-like sea salt crystals was observed under atmospheric conditions with a polarization lidar. The measurements were performed at Barbados (13° N, 59° W) during the SALTRACE winter campaign in February 2014. The radiosonde and Raman lidar observations show a drop in relative humidity below 50 % in the marine aerosol layer simultaneously with a strong increase in particle linear depolarization ratio. Enhanced depolarization ratios (with systematic uncertainty) up to 0.12 ± 0.08 (at 355 nm), 0.15 ± 0.03 (at 532 nm) and 0.10 ± 0.01 (at 1064 nm) were observed and compared to modeling studies of cubic sea salt particles. Lidar-derived correlations of the backscatter coefficient and the depolarization ratio with the relative humidity are reported with a 5-min time resolution. The scattering enhancement due to hygroscopic growth of the marine aerosol particles under atmospheric conditions was determined. Extinction enhancement factors from 40 % to 80 % RH of 2.05 ± 0.82 at 355 nm, 3.73 ± 0.86 at 532 nm and 5.37 ± 1.25 at 1064 nm were found.

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Impact of the particle mixing state on the hygroscopicity of internally mixed sodium chloride-ammonium sulfate single droplets: A theoretical and experimental study

Physical Chemistry Chemical Physics ◽

10.1039/d1cp01574e ◽

2021 ◽

Author(s):

Yeny A. Tobon ◽

Danielle El Hajj ◽

Samantha Seng ◽

Ferdaous Bengrad ◽

Myriam Moreau ◽

...

Keyword(s):

Experimental Study ◽

Sodium Chloride ◽

Ammonium Sulfate ◽

Atmospheric Transport ◽

Sea Salt ◽

Main Constituent ◽

Sea Salt Aerosols ◽

Particle Mixing ◽

Secondary Aerosols ◽

Single Droplets

Sodium chloride (NaCl) is the main constituent of sea-salt aerosols. During atmospheric transport, sea-salt aerosols can interact with gases and other particles including secondary aerosols containing ammonium sulfate ((NH4)2SO4). This...

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