scholarly journals Saharan dust and giant quartz particle transport towards Iceland

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.

Saharan dust episodes and giant quartz particles in Iceland

2021 ◽  
Author(s):  
György Varga ◽  
Pavla Dagsson-Walhauserová ◽  
Fruzsina Gresina ◽  
Agusta Helgadottir
Keyword(s):  
Grain Size ◽  
Saharan Dust ◽  
Atmospheric Environment ◽  
The Arctic ◽  
Dust Particles ◽  
Dust Deposition ◽  
Study Region ◽  
Size And Shape ◽  
Grain Size And Shape ◽  
Local Dust

<p>Saharan dust has an impact on the atmospheric environment and sedimentary units in distant regions. Although Iceland is located within one of the main atmospheric dust pathways moving towards the Arctic, no evidence of Saharan dust deposition has been provided to date for the region. Here we present the results of fourteen Saharan dust episodes, which were identified in Iceland between 2008 to 2020. Aerosol optical depth data of Terra MODIS, HYSPLIT backward trajectories and numerical simulations of Barcelona Supercomputing Center were used in this work to identify the dust episodes. <br>Grain size and shape of the Saharan mineral material deposited in Iceland during two severe deposition events were investigated in detail. Icelandic dust samples from the most active local dust sources were compared with samples of deposited mineral dust from these two severe Saharan dust events to determine their granulometric (complex grain size and shape parameters) and mineralogical characteristics. An automated static optical image analysis technique was applied to thousands of individual particles, and was completed by Raman spectroscopy to identify external quartz particles. <br>Saharan dust episodes were associated with enhanced meridional atmospheric flow patterns driven by unusual meandering jets. Strong southerly 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 pathways of giant Saharan dust particles in the study region, including the first evidence of their deposition in Iceland as previously predicted by models.<br>The support of the National Research, Development, and Innovation Office (projects NKFIH KH130337 and K120620 (for G. Varga)), Czech Science Foundation (project No. 20-06168Y (for P. Dagsson-Waldhauserova)), and COST inDust Action are gratefully acknowledged.</p>

scholarly journals Saharan dust levels in Greece and received inhalation doses

2008 ◽  
Vol 8 (3) ◽  
pp. 11967-11996 ◽  
Author(s):  
C. Mitsakou ◽  
G. Kallos ◽  
N. Papantoniou ◽  
C. Spyrou ◽  
S. Solomos ◽  
...  
Keyword(s):  
Urban Areas ◽  
Particle Deposition ◽  
Mineral Dust ◽  
Weather Conditions ◽  
Pm10 Concentration ◽  
Saharan Dust ◽  
Dust Particles ◽  
Annual Number ◽  
Human Respiratory Tract ◽  
Dust Transport

Abstract. The desert of Sahara is one of the major sources of mineral dust on Earth, producing around 2×108 tons/yr. Under certain weather conditions, dust particles from Saharan desert get transported over the Mediterranean Sea and most of Europe. The limiting values set by the directive EC/30/1999 of European Union can easily be exceeded by the transport of desert dust particles in all south European areas and especially urban. In this study, the effects of dust transport on air quality in several Greek urban areas are quantified. PM10 concentration values from stationary monitoring stations are compared to dust concentrations for the 4-year period 2003–2006. The dust concentration values in the Greek areas were estimated by the SKIRON modelling system coupled with embedded algorithms describing the dust cycle. The mean annual dust contribution to daily-averaged PM10 concentration values was found to be around or even greater than 10% in the urban areas throughout the years examined. Natural dust transport may contribute by much more than 20% to the annual number of exceedances – PM10 values greater than EU limits – depending on the specific monitoring location. In a second stage of the study, the inhaled lung dose received by the residents in various Greek locations is calculated. The particle deposition efficiency of mineral dust at the different parts of the human respiratory tract is determined by applying a lung dosimetry numerical model, which incorporates inhalation dynamics and aerosol physical processes. The inhalation dose from mineral dust particles was greater in the upper respiratory system (extrathoracic region) and less significant in the lungs, especially in the sensitive alveolar region. However, in cases of dust episodes, the amounts of mineral dust deposited along the human lung are comparable to those received during exposure in heavily polluted urban or smoking areas.

scholarly journals Coarse and giant particles are ubiquitous in Saharan dust export regions and are radiatively significant over the Sahara

2020 ◽  
Author(s):  
Claire Ryder ◽  
Eleanor Highwood ◽  
Adrian Walser ◽  
Petra Walser ◽  
Anne Philipp ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Size Range ◽  
State Of The Art ◽  
Chem Phys ◽  
Saharan Dust ◽  
Dust Particles ◽  
Field Campaign ◽  
Dust Transport ◽  
Coarse Mode ◽  
Significant Underestimation

<p>Mineral dust is an important component of the climate system, interacting with radiation, clouds, and biogeochemical systems and impacting atmospheric circulation, air quality, aviation, and solar energy generation. These impacts are sensitive to dust particle size distribution (PSD), yet models struggle or even fail to represent coarse (diameter (<span><em>d</em></span>) <span>>2.5</span> <span>µ</span>m) and giant (<span><em>d</em>>20</span> <span>µ</span>m) dust particles and the evolution of the PSD with transport. Here we examine three state-of-the-art airborne observational datasets, all of which measured the full size range of dust (<span><em>d</em>=0.1</span> to <span>>100</span> <span>µ</span>m) at different stages during transport with consistent instrumentation. We quantify the presence and evolution of coarse and giant particles and their contribution to optical properties using airborne observations over the Sahara (from the Fennec field campaign) and in the Saharan Air Layer (SAL) over the tropical eastern Atlantic (from the AER-D field campaign).</p><p>Observations show significantly more abundant coarse and giant dust particles over the Sahara compared to the SAL: effective diameters of up to 20 <span>µ</span>m were observed over the Sahara compared to 4 <span>µ</span>m in the SAL. Excluding giant particles over the Sahara results in significant underestimation of mass concentration (40 %), as well as underestimates of both shortwave and longwave extinction (18 % and 26 %, respectively, from scattering calculations), while the effects in the SAL are smaller but non-negligible. The larger impact on longwave extinction compared to shortwave implies a bias towards a radiative cooling effect in dust models, which typically exclude giant particles and underestimate coarse-mode concentrations.</p><p>A compilation of the new and published effective diameters against dust age since uplift time suggests that two regimes of dust transport exist. During the initial 1.5 d, both coarse and giant particles are rapidly deposited. During the subsequent 1.5 to 10 d, PSD barely changes with transport, and the coarse mode is retained to a much greater degree than expected from estimates of gravitational sedimentation alone. The reasons for this are unclear and warrant further investigation in order to improve dust transport schemes and the associated radiative effects of coarse and giant particles in models.</p><p>This work has been recently published in ACP (Ryder, C. L., Highwood, E. J., Walser, A., Seibert, P., Philipp, A., and Weinzierl, B.: Coarse and giant particles are ubiquitous in Saharan dust export regions and are radiatively significant over the Sahara, Atmos. Chem. Phys., 19, 15353–15376, https://doi.org/10.5194/acp-19-15353-2019, 2019).</p>

scholarly journals Lidar Measuremnt on Dust Transport from the Saharan Desert to the Iran Plateau

2020 ◽  
Vol 237 ◽  
pp. 02020
Author(s):  
Hossein Panahifar ◽  
Ruhollah Moradhaseli ◽  
Hadi Bourzoie ◽  
Mahdi Gholami ◽  
Hamid Reza Khalesifard
Keyword(s):  
Trajectory Analysis ◽  
Saharan Dust ◽  
Dust Particles ◽  
Raman Lidar ◽  
Dust Layer ◽  
Mean Values ◽  
Dust Transport ◽  
Lidar Ratio ◽  
532 Nm ◽  
Iran Plateau

Optical properties of long-range Saharan dust particles transported to the Iran Plateau have been investigated. The results were derived from the measurements of a dual-wavelength Depolarized backscatter/Raman lidar and a Cimel CE318-2 sunphotometer. Observations were performed in Zanjan, Northwest Iran. The backward trajectory analysis show that the lofted dust plumes come from the Saharan desert and travel along Mediterranean Sea and Turkey toward Iran. The lidar ratio within the lofted dust layer has been found with mean values of 50 sr at 532 nm. For the depolarization ratio, mean values of 25% have been found.

Saharan Dust Records and Its Impact in the European Alps

2021 ◽  
Author(s):  
Marion Greilinger ◽  
Anne Kasper-Giebl
Keyword(s):  
Mineral Dust ◽  
Cloud Condensation Nuclei ◽  
Ice Cores ◽  
Atmospheric Particulate Matter ◽  
Saharan Dust ◽  
Cloud Formation ◽  
Dust Particles ◽  
European Alps ◽  
Airborne Dust ◽  
Dust Events

Mineral dust is one of the main natural sources of atmospheric particulate matter, with the Sahara being one of the most important source regions for the occurrence and deposition of mineral dust in Europe. The occurrence of dust events in the European Alps is documented via measurements of airborne dust and its deposits onto the glaciers. Dust events occur mainly in spring, summer, and early autumn. Dust layers are investigated in ice cores spanning the last millennium as well as in annual snow packs. They strongly affect the overall flux of dust-related compounds (e.g., calcium and magnesium), provide an alkaline input to wet deposition chemistry, and change the microbial abundance and diversity of the snow pack. Still airborne mineral dust particles can act as ice nuclei and cloud condensation nuclei, influencing the formation of cloud droplets and hence cloud formation and precipitation. Dust deposits on the snow lead to a darkening of the surface, referred to as “surface albedo reduction,” which influences the timing of the snowmelt and reduces the annual mass balance of glaciers, showing a direct link to glacier retreat as observed presently in a warming climate.

scholarly journals Effects of three-dimensional electric field on saltation during dust storms: An observational and numerical study

2019 ◽  
Author(s):  
Huan Zhang ◽  
You-He Zhou
Keyword(s):  
Electric Field ◽  
Field Data ◽  
Numerical Study ◽  
Three Dimensional ◽  
Vertical Component ◽  
Dust Storms ◽  
Dust Particles ◽  
Sand Transport ◽  
Dust Transport ◽  
Dust Events

Abstract. Particle tribo-electrification being ubiquitous in nature and industry, potentially plays a key role in dust events, including the lifting and transport of sand and dust particles. However, the properties of electric field (E-field) and its influences on saltation during dust storms remain obscure as the high complexity of dust storms and the existing numerical studies mainly limited to one-dimensional (1-D) E-field. Here, we quantify the effects of real three-dimensional (3-D) E-field on saltation, through a combination of field observations and numerical modelling. The 3-D E-fields in the sub-meter layer from 0.05 to 0.7 m above the ground during a dust storm are measured at Qingtu Lake Observation Array site. The measured results show that each component of the 3-D E-field data nearly collapses on a single 3-order polynomial curve when normalized. Interestingly, the vertical component of the 3-D E-field increases with increasing height in the saltation layer during dust storms. Such 3-D E-field data close to the ground within a few centimeters has never been reported and formulated before. Using the discrete element method, we then develop a comprehensive saltation model, in which the tribo-electrification between particle-particle midair collisions is explicitly accounted for, allowing us to evaluate the tribo-electrification in saltation properly. By combining the results of measurements and modelling, we find that although the vertical component of the E-field (i.e. 1-D E-field) inhibits sand transport, 3-D E-field enhances sand transport substantially. Furthermore, the model predicts that 3-D E-field enhances the total mass flux by up to 63 %. This suggests that a truly 3-D E-field consideration is necessary if one is to explain precisely how the E-field affects saltation during dust storms. These results will further improve our understanding of particle tribo-electrification in saltation and help to provide more accurate characterizations of sand and dust transport during dust storms.

scholarly journals Saharan dust levels in Greece and received inhalation doses

2008 ◽  
Vol 8 (23) ◽  
pp. 7181-7192 ◽  
Author(s):  
C. Mitsakou ◽  
G. Kallos ◽  
N. Papantoniou ◽  
C. Spyrou ◽  
S. Solomos ◽  
...  
Keyword(s):  
Urban Areas ◽  
Particle Deposition ◽  
Mineral Dust ◽  
Pm10 Concentration ◽  
Saharan Dust ◽  
Anthropogenic Sources ◽  
Dust Particles ◽  
Annual Number ◽  
Human Respiratory Tract ◽  
Dust Transport

Abstract. The desert of Sahara is one of the major sources of mineral dust on Earth, producing around 2×108 tons/yr. Under certain weather conditions, dust particles from Saharan desert get transported over the Mediterranean Sea and most of Europe. The limiting values set by the directive EC/30/1999 of European Union can easily be exceeded by the transport of desert dust particles in the south European Region and especially in urban areas, where there is also significant contribution from anthropogenic sources. In this study, the effects of dust transport on air quality in several Greek urban areas are quantified. PM10 concentration values from stationary monitoring stations are compared to dust concentrations for the 4-year period 2003–2006. The dust concentration values in the Greek areas were estimated by the SKIRON modelling system coupled with embedded algorithms describing the dust cycle. The mean annual dust contribution to daily-averaged PM10 concentration values was found to be around or even greater than 10% in the urban areas throughout the years examined. Natural dust transport may contribute by more than 20% to the annual number of exceedances – PM10 values greater than EU limits – depending on the specific monitoring location. In a second stage of the study, the inhaled lung dose received by the residents in various Greek locations is calculated. The particle deposition efficiency of mineral dust at the different parts of the human respiratory tract is determined by applying a lung dosimetry numerical model, which incorporates inhalation dynamics and aerosol physical processes. The inhalation dose from mineral dust particles was greater in the upper respiratory system (extrathoracic region) and less significant in the lungs, especially in the sensitive alveolar region. However, in cases of dust episodes, the amounts of mineral dust deposited along the human lung are comparable to those received during exposure in heavily polluted urban or smoking areas.

scholarly journals Coarse and giant particles are ubiquitous in Saharan dust export regions and are radiatively significant over the Sahara

2019 ◽  
Vol 19 (24) ◽  
pp. 15353-15376 ◽  
Author(s):  
Claire L. Ryder ◽  
Eleanor J. Highwood ◽  
Adrian Walser ◽  
Petra Seibert ◽  
Anne Philipp ◽  
...  
Keyword(s):  
Mass Concentration ◽  
Size Range ◽  
State Of The Art ◽  
Saharan Dust ◽  
Dust Particles ◽  
Field Campaign ◽  
Dust Transport ◽  
Saharan Air Layer ◽  
Coarse Mode ◽  
Significant Underestimation

Abstract. Mineral dust is an important component of the climate system, interacting with radiation, clouds, and biogeochemical systems and impacting atmospheric circulation, air quality, aviation, and solar energy generation. These impacts are sensitive to dust particle size distribution (PSD), yet models struggle or even fail to represent coarse (diameter (d) >2.5 µm) and giant (d>20 µm) dust particles and the evolution of the PSD with transport. Here we examine three state-of-the-art airborne observational datasets, all of which measured the full size range of dust (d=0.1 to >100 µm) at different stages during transport with consistent instrumentation. We quantify the presence and evolution of coarse and giant particles and their contribution to optical properties using airborne observations over the Sahara (from the Fennec field campaign) and in the Saharan Air Layer (SAL) over the tropical eastern Atlantic (from the AER-D field campaign). Observations show significantly more abundant coarse and giant dust particles over the Sahara compared to the SAL: effective diameters of up to 20 µm were observed over the Sahara compared to 4 µm in the SAL. Excluding giant particles over the Sahara results in significant underestimation of mass concentration (40 %), as well as underestimates of both shortwave and longwave extinction (18 % and 26 %, respectively, from scattering calculations), while the effects in the SAL are smaller but non-negligible. The larger impact on longwave extinction compared to shortwave implies a bias towards a radiative cooling effect in dust models, which typically exclude giant particles and underestimate coarse-mode concentrations. A compilation of the new and published effective diameters against dust age since uplift time suggests that two regimes of dust transport exist. During the initial 1.5 d, both coarse and giant particles are rapidly deposited. During the subsequent 1.5 to 10 d, PSD barely changes with transport, and the coarse mode is retained to a much greater degree than expected from estimates of gravitational sedimentation alone. The reasons for this are unclear and warrant further investigation in order to improve dust transport schemes and the associated radiative effects of coarse and giant particles in models.

scholarly journals Dust–air pollution dynamics over the eastern Mediterranean

2015 ◽  
Vol 15 (16) ◽  
pp. 9173-9189 ◽  
Author(s):  
M. Abdelkader ◽  
S. Metzger ◽  
R. E. Mamouri ◽  
M. Astitha ◽  
L. Barrie ◽  
...  
Keyword(s):  
Air Pollution ◽  
Eastern Mediterranean ◽  
Tropospheric Chemistry ◽  
Saharan Dust ◽  
Dust Particles ◽  
Back Trajectory ◽  
Dust Deposition ◽  
Dust Transport ◽  
Frontal Systems ◽  
Scavenging Efficiency

Abstract. Interactions of desert dust and air pollution over the eastern Mediterranean (EM) have been studied, focusing on two distinct dust transport events on 22 and 28 September 2011. The atmospheric chemistry–climate model EMAC has been used at about 50 km grid spacing, applying an online dust emission scheme and calcium as a proxy for dust reactivity. EMAC includes a detailed tropospheric chemistry mechanism, aerosol microphysics and thermodynamics schemes to describe dust "aging". The model is evaluated using ground-based observations for aerosol concentrations and aerosol optical depth (AOD) as well as satellite observations. Simulation results and back trajectory analysis show that the development of synoptic disturbances over the EM can enhance dust transport from the Sahara and Arabian deserts in frontal systems that also carry air pollution to the EM. The frontal systems are associated with precipitation that controls the dust removal. Our results show the importance of chemical aging of dust, which increases particle size, dust deposition and scavenging efficiency during transport, overall reducing the lifetime relative to non-aged dust particles. The relatively long travel periods of Saharan dust result in more sustained aging compared to Arabian dust. Sensitivity simulations indicate 3 times more dust deposition of aged relative to pristine dust, which significantly decreases the dust lifetime and loading.

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