Chemical aging of atmospheric mineral dust during transatlantic transport

Abstract. Transatlantic dust transport has many implications for the atmosphere, ocean and climate. We present a modeling study on the impact of the key processes (dust emissions flux, convection and dust aging parameterizations) that control the transatlantic dust transport. Typically, the Inter-Tropical Convergence Zone (ITCZ) acts as a barrier for the meridional dust transport. To characterize the dust outflow over the Atlantic Ocean, we address two regional phenomena: (i) dust interactions with the ITCZ (DIZ) and (ii) the adjacent dust transport over the Atlantic Ocean (DTA). In the DTA zone, the dust loading shows a steep and linear gradient westward over the Atlantic Ocean where particle sedimentation is the dominant removal process, whereas in the DIZ zone cloud interactions and wet deposition predominate. To study the different impacts of aging, we present two case studies that exclude condensation and coagulation, and include dust aging at various levels of complexity. For dust aging, we consider the uptake of inorganic acids on the surface of mineral particles that form salt compounds. Calcium, used as a proxy for the overall chemically reactive dust fraction, drives the dust-related neutralization reactions leading to higher dust aerosol optical depth (AOD). The aged dust particles are transferred to the soluble aerosol modes in the model and are mixed with other species that originate from anthropogenic and natural sources. The neutralization products (salts) take up water vapor from the atmosphere and increase the dust AOD under subsaturated conditions. We define the "direct effect of dust aging" to refer to the increase in AOD as a result of hygroscopic growth. On the other hand, the aged dust is more efficiently removed (wet and dry) because of the increase in particle size and hygroscopicity. This more efficient removal reduces the dust AOD over the DIZ zone. We define this as the "indirect effect of dust aging", complementary to the direct effect that is dominant in the DTA zone. Distinction of the two aging effects helps develop insight into the regional importance of dust–air-pollution interactions.

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Sensitivity of transatlantic dust transport to chemical aging and related atmospheric processes

Atmospheric Chemistry and Physics ◽

10.5194/acp-17-3799-2017 ◽

2017 ◽

Vol 17 (6) ◽

pp. 3799-3821 ◽

Cited By ~ 16

Author(s):

Mohamed Abdelkader ◽

Swen Metzger ◽

Benedikt Steil ◽

Klaus Klingmüller ◽

Holger Tost ◽

...

Keyword(s):

Atlantic Ocean ◽

Wet Deposition ◽

Dust Emission ◽

Dust Particles ◽

Emission Flux ◽

Dust Transport ◽

Chemical Aging ◽

Calcium Cation ◽

Convection Schemes ◽

The Impact

Abstract. We present a sensitivity study on transatlantic dust transport, a process which has many implications for the atmosphere, the ocean and the climate. We investigate the impact of key processes that control the dust outflow, i.e., the emission flux, convection schemes and the chemical aging of mineral dust, by using the EMAC model following Abdelkader et al. (2015). To characterize the dust outflow over the Atlantic Ocean, we distinguish two geographic zones: (i) dust interactions within the Intertropical Convergence Zone (ITCZ), or the dust–ITCZ interaction zone (DIZ), and (ii) the adjacent dust transport over the Atlantic Ocean (DTA) zone. In the latter zone, the dust loading shows a steep and linear gradient westward over the Atlantic Ocean since particle sedimentation is the dominant removal process, whereas in the DIZ zone aerosol–cloud interactions, wet deposition and scavenging processes determine the extent of the dust outflow. Generally, the EMAC simulated dust compares well with CALIPSO observations; however, our reference model configuration tends to overestimate the dust extinction at a lower elevation and underestimates it at a higher elevation. The aerosol optical depth (AOD) over the Caribbean responds to the dust emission flux only when the emitted dust mass is significantly increased over the source region in Africa by a factor of 10. These findings point to the dominant role of dust removal (especially wet deposition) in transatlantic dust transport. Experiments with different convection schemes have indeed revealed that the transatlantic dust transport is more sensitive to the convection scheme than to the dust emission flux parameterization. To study the impact of dust chemical aging, we focus on a major dust outflow in July 2009. We use the calcium cation as a proxy for the overall chemical reactive dust fraction and consider the uptake of major inorganic acids (i.e., H2SO4, HNO3 and HCl) and their anions, i.e., sulfate (SO42−), bisulfate (HSO4−), nitrate (NO3−) and chloride (Cl−), on the surface of mineral particles. The subsequent neutralization reactions with the calcium cation form various salt compounds that cause the uptake of water vapor from the atmosphere, i.e., through the chemical aging of dust particles leading to an increase of 0.15 in the AOD under subsaturated conditions (July 2009 monthly mean). As a result of the radiative feedback on surface winds, dust emissions increased regionally. On the other hand, the aged dust particles, compared to the non-aged particles, are more efficiently removed by both wet and dry deposition due to the increased hygroscopicity and particle size (mainly due to water uptake). The enhanced removal of aged particles decreases the dust burden and lifetime, which indirectly reduces the dust AOD by 0.05 (monthly mean). Both processes can be significant (major dust outflow, July 2009), but the net effect depends on the region and level of dust chemical aging.

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Microscale dynamics between dust and microorganisms in alpine snowpack

10.21079/11681/40079 ◽

2021 ◽

Author(s):

Alison Thurston ◽

Zoe Courville ◽

Lauren Farnsworth ◽

Ross Lieblappen ◽

Shelby Rosten ◽

...

Keyword(s):

Mechanical Properties ◽

Dust Particles ◽

Dust Deposition ◽

Dust Transport ◽

Source Regions ◽

Chemical Signatures ◽

Scale Properties ◽

Bacteria And Fungi ◽

The Impact ◽

Snow Samples

Dust particles carry microbial and chemical signatures from source regions to deposition regions. Dust and its occupying microorganisms are incorporated into, and can alter, snowpack physical properties including snow structure and resultant radiative and mechanical properties that in turn affect larger-scale properties, including surrounding hydrology and maneuverability. Microorganisms attached to deposited dust maintain genetic evidence of source substrates and can be potentially used as bio-sensors. The objective of this study was to investigate the impact of dust-associated microbial deposition on snowpack and microstructure. As part of this effort, we characterized the microbial communities deposited through dust transport, examined dust provenance, and identified the microscale location and fate of dust within a changing snow matrix. We found dust characteristics varied with deposition event and that dust particles were generally embedded in the snow grains, with a small fraction of the dust particles residing on the exterior of the snow matrix. Dust deposition appears to retard expected late season snow grain growth. Both bacteria and fungi were identified in the collected snow samples.

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Satellite inference of water vapor and aerosol-above-cloud combined effect on radiative budget and cloud top processes in the Southeast Atlantic Ocean

10.5194/acp-2019-189 ◽

2019 ◽

Author(s):

Lucia T. Deaconu ◽

Nicolas Ferlay ◽

Fabien Waquet ◽

Fanny Peers ◽

François Thieuleux ◽

...

Keyword(s):

Water Vapor ◽

Atlantic Ocean ◽

Direct Effect ◽

Radiative Forcing ◽

Ambient Air ◽

Global Climate Models ◽

Entrainment Rate ◽

Cloud Properties ◽

Absorbing Aerosols ◽

The Impact

Abstract. Aerosols have a direct effect on the Earth's radiative budget and can also affect the cloud development and lifetime. The aerosols above clouds (AAC) are particularly associated with high uncertainties in global climate models. Therefore, it is prerequisite to improve the description and understanding of these situations. During the austral winter, large loadings of biomass burning aerosols originating from fires in the southern African subcontinent are lifted and transported long distances westwards, across the Southeast Atlantic Ocean. The negligible wet scavenging of these absorbing aerosols leads to a near-persistent smoke layer above one of the largest stratocumulus cloud deck on the planet. Therefore, the Southeast Atlantic region is a very important area for studying the impact of above cloud absorbing aerosols, their radiative forcing and their possible effects on clouds. In this study we aim to analyse and quantify the effect of smoke loadings on cloud properties using a synergy of different remote sensing technics from A-Train retrievals (methods based on the passive instruments POLDER and MODIS and the operational method of the spaceborne lidar CALIOP), collocated with ERA-Interim re-analysis meteorological profiles. To analyse the possible mechanisms of AACs effects on cloud properties, we developed a high and low aerosol loading approach, that consists in evaluating the change in radiative quantities (i.e. cloud top cooling, heating rate vertical profiles) and cloud properties with the smoke loading. During this analysis, we account for the variation in the meteorological conditions over our sample area. The results show that the region we focus on is primarily under the energetic influence of absorbing aerosols, leading to a significant positive shortwave direct effect at the top of the atmosphere. For larger loads of AACs, clouds are optically thicker, with an increase in liquid water path of 20 g m−2 and lower cloud top altitudes by 100 m. These results do not contradict the semi-direct effect of above cloud aerosols, explored in previous studies. Furthermore, we observe a strong correlation between the aerosol and the water vapor loadings, which has to be accounted for. A detailed analysis of the heating rates shows that the absorbing aerosols are 90 % responsible for warming the ambient air where they reside, with approximately + 5.7 K/day, while the accompanying water vapour above clouds has a longwave effect of + 4.7 K/day (equivalent to 7 % decrease) on the cloud top cooling. We infer that this decreased cloud top cooling in particular, in addition with the higher humidity above the clouds, might modify the cloud top entrainment rate and its effect, leading to thicker clouds. Therefore, smoke (the combination of aerosol and water vapor) events would have the potential to modify and probably reinforce the underlaying cloud cover.

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Transport of dust particles from the Bodélé region to the monsoon layer: AMMA case study of the 9–14 June 2006 period

Atmospheric Chemistry and Physics Discussions ◽

10.5194/acpd-10-5051-2010 ◽

2010 ◽

Vol 10 (2) ◽

pp. 5051-5090 ◽

Cited By ~ 4

Author(s):

S. Crumeyrolle ◽

P. Tulet ◽

L. Garcia-Carreras ◽

C. Flamant ◽

D. J. Parker ◽

...

Keyword(s):

Boundary Layer ◽

Dust Particle ◽

Particle Concentration ◽

Strong Relationship ◽

Atmospheric Model ◽

Dust Particles ◽

Particle Sedimentation ◽

Surface Cover ◽

Mesoscale Atmospheric Model ◽

The Impact

Abstract. Aerosol properties were measured during an airborne campaign experiment that took place in June 2006 in West Africa within the framework of the African Monsoon Multidisciplinary Analyses (AMMA). The goal of the present study was to determine the process that facilitates the sedimentation of dust particles from the Saharan Air Layer (SAL) to the boundary layer. A significant change in the dust particle concentration measured along the meridian between Niamey (Niger) and Cotonou (Benin) was found in the boundary layer (~700 m), where the dust particle concentration increased in a zone where local emission is not possible. Moreover, the boundary layer top observed with the dropsondes launched with the F-F20 shows a strong relationship with the surface cover anomalies, with higher Boundary Layer (BL) tops over the warmer surfaces, such as croplands, as opposed to adjacent forest. A mesoscale atmospheric model with a new on-line dust parameterization, resulting from the Alfaro and Gomes (2001) parametrisation and AMMA observations, was used to interpret the impact of vegetation anomalies on dust particle sedimentation. The results of the simulation are consistent with the observations, with higher dust over the warm surface cover anomalies.

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Satellite inference of water vapour and above-cloud aerosol combined effect on radiative budget and cloud-top processes in the southeastern Atlantic Ocean

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-11613-2019 ◽

2019 ◽

Vol 19 (17) ◽

pp. 11613-11634 ◽

Cited By ~ 4

Author(s):

Lucia T. Deaconu ◽

Nicolas Ferlay ◽

Fabien Waquet ◽

Fanny Peers ◽

François Thieuleux ◽

...

Keyword(s):

Atlantic Ocean ◽

Heating Rate ◽

Water Vapour ◽

Direct Effect ◽

Ambient Air ◽

Cloud Properties ◽

Smoke Layer ◽

Absorbing Aerosols ◽

The Impact ◽

Southeastern Atlantic

Abstract. Aerosols have a direct effect on the Earth's radiative budget and can also affect cloud development and lifetime, and the aerosols above clouds (AAC) are particularly associated with high uncertainties in global climate models. Therefore, it is a prerequisite to improve the description and understanding of these situations. During the austral winter, large loadings of biomass burning aerosols originating from fires in the southern African subcontinent are lifted and transported westwards, across the southeastern Atlantic Ocean. The negligible wet scavenging of these absorbing aerosols leads to a near-persistent smoke layer above one of the largest stratocumulus cloud decks on the planet. Therefore, the southeastern Atlantic region is a very important area for studying the impact of above-cloud absorbing aerosols, their radiative forcing and their possible effects on clouds. In this study we aim to analyse and quantify the effect of smoke loadings on cloud properties using a synergy of different remote sensing techniques from A-Train retrievals (methods based on the passive instruments POLDER and MODIS and the operational method of the spaceborne lidar CALIOP), collocated with ERA-Interim re-analysis meteorological profiles. To analyse the possible mechanisms of AAC effects on cloud properties, we developed a high and low aerosol loading approach, which consists in evaluating the change in radiative quantities (i.e. cloud-top cooling, heating rate vertical profiles) and cloud properties with the smoke loading. During this analysis, we account for the variation in the meteorological conditions over our sample area by selecting the months associated with one meteorological regime (June–August). The results show that the region we focus on is primarily under the energetic influence of absorbing aerosols, leading to a significant positive shortwave direct effect at the top of the atmosphere. For larger loads of AACs, clouds are optically thicker, with an increase in liquid water path of 20 g m−2 and lower cloud-top altitudes by 100 m. These results do not contradict the semi-direct effect of above-cloud aerosols, explored in previous studies. Furthermore, we observe a strong covariance between the aerosol and the water vapour loadings, which has to be accounted for. A detailed analysis of the heating rate profiles shows that within the smoke layer, the absorbing aerosols are 90 % responsible for warming the ambient air by approximately 5.7 K d−1. The accompanying water vapour, however, has a longwave effect at distance on the cloud top, reducing its cooling by approximately 4.7 K d−1 (equivalent to 7 %). We infer that this decreased cloud-top cooling in particular, in addition with the higher humidity above the clouds, might modify the cloud-top entrainment rate and its effect, leading to thicker clouds. Therefore, smoke (the combination of aerosol and water vapour) events would have the potential to modify and probably reinforce the underlaying cloud cover.

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Transport of dust particles from the Bodélé region to the monsoon layer – AMMA case study of the 9–14 June 2006 period

Atmospheric Chemistry and Physics ◽

10.5194/acp-11-479-2011 ◽

2011 ◽

Vol 11 (2) ◽

pp. 479-494 ◽

Cited By ~ 28

Author(s):

S. Crumeyrolle ◽

P. Tulet ◽

L. Gomes ◽

L. Garcia-Carreras ◽

C. Flamant ◽

...

Keyword(s):

Boundary Layer ◽

Dust Particle ◽

Particle Concentration ◽

Strong Relationship ◽

Atmospheric Model ◽

Dust Particles ◽

Particle Sedimentation ◽

Dynamical Mechanism ◽

Surface Cover ◽

The Impact

Abstract. Aerosol properties were measured during an airborne campaign experiment that took place in June 2006 in West Africa within the framework of the African Monsoon Multidisciplinary Analyses (AMMA). The goal of the present study was to investigate a dynamical mechanism able to facilitate the sedimentation of dust particles from the Saharan Air Layer (SAL) into the boundary layer. A significant change in the dust particle concentration measured along the meridian between Niamey (Niger) and Cotonou (Benin) was found in the boundary layer (~700 m), where the dust particle concentration increased in a zone where local emission is not possible. Moreover, the boundary layer top observed with the dropsondes launched with the F-F20 shows a strong relationship with the surface cover anomalies, with higher Boundary Layer (BL) tops over the warmer surfaces, such as croplands, as opposed to adjacent forest. A mesoscale atmospheric model with a new on-line dust parameterization, resulting from the Alfaro and Gomes (2001) parametrisation and AMMA observations, was used to interpret the impact of vegetation anomalies on dust particle sedimentation. The results of the simulation are consistent with the observations, with higher dust concentration over the warm surface cover anomalies.

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Impact of dust and sand storms on the aviation operation and assessment of conditions for their occurrence at aerodromes in European Russia

Hydrometeorological research and forecasting ◽

10.37162/2618-9631-2020-4-78-95 ◽

2020 ◽

Vol 4 ◽

pp. 78-95

Author(s):

A.R. Ivanova ◽

◽

E.N. Skriptunova ◽

N.I. Komasko ◽

A.A. Zavialova ◽

...

Keyword(s):

Seasonal Variations ◽

Dust Storms ◽

European Russia ◽

Air Transport ◽

Review Of Literature ◽

Dust Transport ◽

Air Masses ◽

The Past ◽

Sand Storm ◽

The Impact

A review of literature on the impact of dust and sand storms on the air transport operation is presented. Observational data on dust storms at the aerodromes of European Russia for the period of 2001-2019 are analyzed. The seasonal variations in dust transport episodes at aerodromes and its relationship with visibility changes are discussed. The characteristics of dusty air masses and advection are given. It is concluded that the frequency of dust transfer episodes for the aerodromes under study has decreased over the past five years, except for Gumrak aerodrome (Volgograd). Keywords: dust storm, sand storm, aviation, visibility, seasonal variations, aerodrome оf European Russia

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The Impact of Ambient Atmospheric Mineral-Dust Particles on the Calcification of Lungs

Minerals ◽

10.3390/min11020125 ◽

2021 ◽

Vol 11 (2) ◽

pp. 125

Author(s):

Mariola Jabłońska ◽

Janusz Janeczek ◽

Beata Smieja-Król

Keyword(s):

Mineral Dust ◽

Smoking Habit ◽

Lower Lobe ◽

Ambient Air ◽

Dust Particles ◽

Masking Effect ◽

Amorphous Calcium Carbonate ◽

Calcium Salts ◽

The Impact ◽

First Time

For the first time, it is shown that inhaled ambient air-dust particles settled in the human lower respiratory tract induce lung calcification. Chemical and mineral compositions of pulmonary calcium precipitates in the lung right lower-lobe (RLL) tissues of 12 individuals who lived in the Upper Silesia conurbation in Poland and who had died from causes not related to a lung disorder were determined by transmission and scanning electron microscopy. Whereas calcium salts in lungs are usually reported as phosphates, calcium salts precipitated in the studied RLL tissue were almost exclusively carbonates, specifically Mg-calcite and calcite. These constituted 37% of the 1652 mineral particles examined. Mg-calcite predominated in the submicrometer size range, with a MgCO3 content up to 50 mol %. Magnesium plays a significant role in lung mineralization, a fact so far overlooked. The calcium phosphate (hydroxyapatite) content in the studied RLL tissue was negligible. The predominance of carbonates is explained by the increased CO2 fugacity in the RLL. Carbonates enveloped inhaled mineral-dust particles, including uranium-bearing oxides, quartz, aluminosilicates, and metal sulfides. Three possible pathways for the carbonates precipitation on the dust particles are postulated: (1) precipitation of amorphous calcium carbonate (ACC), followed by its transformation to calcite; (2) precipitation of Mg-ACC, followed by its transformation to Mg-calcite; (3) precipitation of Mg-free ACC, causing a localized relative enrichment in Mg ions and subsequent heterogeneous nucleation and crystal growth of Mg-calcite. The actual number of inhaled dust particles may be significantly greater than was observed because of the masking effect of the carbonate coatings. There is no simple correlation between smoking habit and lung calcification.

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Evaluation of Marblewood Dust’s (Marmaroxylon racemosum) Effect on Ignition Risk

Applied Sciences ◽

10.3390/app11156874 ◽

2021 ◽

Vol 11 (15) ◽

pp. 6874

Author(s):

Miroslava Vandličkova ◽

Iveta Markova ◽

Katarina Holla ◽

Stanislava Gašpercová

Keyword(s):

Particle Size ◽

Dust Particles ◽

Wood Dust ◽

Sieve Analysis ◽

Granulometric Analysis ◽

Analysis Measurement ◽

Risk Research ◽

Minimum Ignition Temperature ◽

The Impact

The paper deals with the selected characteristics, such as moisture, average bulk density, and fraction size, of tropical marblewood dust (Marmaroxylon racemosum) that influence its ignition risk. Research was focused on sieve analysis, granulometric analysis, measurement of moisture level in the dust, and determination of the minimum ignition temperatures of airborne tropical dust and dust layers. Samples were prepared using a Makita 9556CR 1400W grinder and K36 sandpaper for the purpose of selecting the percentages of the various fractions (<63, 63, 71, 100, 200, 315, 500 μm). The samples were sized on an automatic vibratory sieve machine Retsch AS 200. More than 65% of the particles were determined to be under 100 μm. The focus was on microfractions of tropical wood dust (particles with a diameter of ≤100 µm) and on the impact assessment of particle size (particle size <100 µm) on the minimum ignition temperatures of airborne tropical dust and dust layers. The minimum ignition temperature of airborne marblewood dust decreased with the particle size to the level of 400 °C (particle size 63 μm).

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Saharan dust and giant quartz particle transport towards Iceland

Scientific Reports ◽

10.1038/s41598-021-91481-z ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

György Varga ◽

Pavla Dagsson-Walhauserová ◽

Fruzsina Gresina ◽

Agusta Helgadottir

Keyword(s):

Numerical Models ◽

Saharan Dust ◽

Atmospheric Environment ◽

The Arctic ◽

Dust Particles ◽

Atmospheric Flow ◽

Dust Transport ◽

Strong Winds ◽

Dust Events ◽

Local Dust

AbstractMineral dust emissions from Saharan sources have an impact on the atmospheric environment and sedimentary units in distant regions. Here, we present the first systematic observations of long-range Saharan dust transport towards Iceland. Fifteen Saharan dust episodes were identified to have occurred between 2008 and 2020 based on aerosol optical depth data, backward trajectories and numerical models. Icelandic samples from the local dust sources were compared with deposited dust from two severe Saharan dust events in terms of their granulometric and mineralogical characteristics. The episodes were associated with enhanced meridional atmospheric flow patterns driven by unusual meandering jets. Strong winds were able to carry large Saharan quartz particles (> 100 µm) towards Iceland. Our results confirm the atmospheric pathways of Saharan dust towards the Arctic, and identify new northward meridional long-ranged transport of giant dust particles from the Sahara, including the first evidence of their deposition in Iceland as previously predicted by models.

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