A modeling insight into the transport of large dust particles

2021 ◽  
Author(s):  
Eleni Drakaki ◽  
Alexandra Tsekeri ◽  
Vasillis Amiridis ◽  
Stavros Solomos ◽  
Antonis Gkikas ◽  
...  
Keyword(s):  
Size Distribution ◽  
Mineral Dust ◽  
Saharan Dust ◽  
Cloud Formation ◽  
Dust Particles ◽  
Negative Effects ◽  
Airborne Dust ◽  
Horizon 2020 ◽  
Research And Innovation ◽  
The Impact

<p>Mineral dust is an important component of the climate system, affecting radiation, cloud formation, biogeochemical cycles, as well as having negative effects on solar energy budget and human health. All these processes are affected from the size of the particles which is significantly underestimated by the Earth System Models. Here, we present results from a first attempt to modify the size distribution parameterizations in the GOCART-AFWA dust scheme of WRF - Chem, by including the large dust particles with diameters greater than 20 µm to describe the mineral dust cycle. The parameterization is based on Saharan dust observational datasets from FENNEC and SAMUM campaigns. We investigate the impact of the extended size distribution on the overall transported dust load and also the impact of particle settling considerations in deposition rates. The model results are compared with airborne dust measurements from AER-D campaign. In order to achieve the best agreement with the observations, an artificial force that counteracts gravity approximately by 80% for the large particles is needed, indicating the presence of one or more under-represented physical processes in the model.</p><p><strong>Acknowledgment:</strong> This research was supported by D-TECT (Grant Agreement 725698) funded by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme. </p>

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 Impact of mineral dust on cloud formation in a Saharan outflow region

2011 ◽  
Vol 11 (12) ◽  
pp. 32363-32390 ◽  
Author(s):  
L. Smoydzin ◽  
A. Teller ◽  
H. Tost ◽  
M. Fnais ◽  
J. Lelieveld
Keyword(s):  
Radiative Forcing ◽  
Mineral Dust ◽  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Coupled Model ◽  
Cloud Formation ◽  
Dust Particles ◽  
Ice Nuclei ◽  
Outflow Region ◽  
The Impact

Abstract. We present a numerical modelling study investigating the impact of mineral dust on cloud formation over the Eastern Mediterranean for two case studies: (i) 25 September 2008 and (ii) 28/29 January 2003. On both days dust plumes crossed the Mediterranean and interacted with clouds forming along frontal systems. For our investigation we used the fully online coupled model WRF-chem. The results show that increased aerosol concentrations due to the presence of mineral dust can enhance the formation of ice crystals. This leads to slight shifts of the spatial and temporal precipitation patterns compared to scenarios where dust was not considered to act as ice nuclei. However, the total amount of precipitation did not change significantly. The only exception occurred when dust entered into an area of orographic ascent, causing glaciation of the clouds, leading to a local enhancement of rainfall. The impact of dust particles acting as giant cloud condensation nuclei on precipitation formation was found to be small. Based on our simulations the contribution of dust to the CCN population is potentially significant only for warm phase clouds. Nevertheless, the dust-induced differences in the microphysical structure of the clouds can contribute to a significant radiative forcing.

scholarly journals The impact of mineral dust on cloud formation during the Saharan dust event in April 2014 over Europe

2018 ◽  
Author(s):  
Michael Weger ◽  
Bernd Heinold ◽  
Ina Tegen ◽  
Christa Engler ◽  
Patric Seifert ◽  
...  
Keyword(s):  
Cloud Cover ◽  
Mineral Dust ◽  
Dust Cloud ◽  
Ice Nucleation ◽  
Saharan Dust ◽  
Cloud Formation ◽  
Cirrus Cloud ◽  
Dust Event ◽  
The Impact

Abstract. A regional modeling study on the impact of desert dust on cloud formation is presented for a major Saharan dust outbreak over Europe from 2 April to 5 April 2014. The dust event coincided with an extensive and dense cirrus cloud layer, suggesting an influence of dust on atmospheric ice nucleation. Using interactive simulation with the regional dust model COSMO-MUSCAT, we investigate cloud and precipitation representation in the model and test the sensitivity of cloud parameters to dust-cloud and dust-radiation interactions of the simulated dust plume. We evaluate model results with ground-based and space-borne remote sensings of aerosol and cloud properties, as well as the in situ measurements obtained during the ML-CIRRUS aircraft campaign. A run of the model with single-moment bulk microphysics without online dust feedback considerably underestimated cirrus cloud cover over Germany in the comparison with infrared satellite imagery. This was also reflected in simulated upper-tropospheric ice water content (IWC), which accounted only for 20 % of the observed values. The interactive dust simulation with COSMO-MUSCAT, including a two-moment bulk microphysics scheme and dust-cloud as well as dust-radiation feedback, in contrast, led to significant improvements. The modeled cirrus cloud cover and IWC were by at least a factor of two higher in the relevant altitudes compared to the non-interactive model run. We attributed these improvements mainly to enhanced deposition freezing in response to the high mineral dust concentrations. This was corroborated further in a significant decrease in ice particle radii towards more realistic values, as compared to in situ measurements from the ML-CIRRUS aircraft campaign. By testing different empirical ice nucleation parameterizations, we further demonstrate that remaining uncertainties in the ice nucleating properties of mineral dust affect the model performance at least as significantly as to whether including the online representation of the mineral distribution. Dust-radiation interactions played a secondary role for cirrus cloud formation, but contributed to a more realistic representation of precipitation by suppressing moist convection in southern Germany. In addition, a too low specific humidity in the 7 to 10 km altitude range in the boundary conditions was identified as a main reason of misrepresentation of cirrus clouds in this model study.

scholarly journals The impact of mineral dust on cloud formation during the Saharan dust event in April 2014 over Europe

2018 ◽  
Vol 18 (23) ◽  
pp. 17545-17572 ◽  
Author(s):  
Michael Weger ◽  
Bernd Heinold ◽  
Christa Engler ◽  
Ulrich Schumann ◽  
Axel Seifert ◽  
...  
Keyword(s):  
Cloud Cover ◽  
Mineral Dust ◽  
Dust Cloud ◽  
Ice Nucleation ◽  
Saharan Dust ◽  
Cloud Formation ◽  
Cirrus Cloud ◽  
Dust Event ◽  
The Impact

Abstract. A regional modeling study on the impact of desert dust on cloud formation is presented for a major Saharan dust outbreak over Europe from 2 to 5 April 2014. The dust event coincided with an extensive and dense cirrus cloud layer, suggesting an influence of dust on atmospheric ice nucleation. Using interactive simulation with the regional dust model COSMO-MUSCAT, we investigate cloud and precipitation representation in the model and test the sensitivity of cloud parameters to dust–cloud and dust–radiation interactions of the simulated dust plume. We evaluate model results with ground-based and spaceborne remote sensing measurements of aerosol and cloud properties, as well as the in situ measurements obtained during the ML-CIRRUS aircraft campaign. A run of the model with single-moment bulk microphysics without online dust feedback considerably underestimated cirrus cloud cover over Germany in the comparison with infrared satellite imagery. This was also reflected in simulated upper-tropospheric ice water content (IWC), which accounted for only 20 % of the observed values. The interactive dust simulation with COSMO-MUSCAT, including a two-moment bulk microphysics scheme and dust–cloud as well as dust–radiation feedback, in contrast, led to significant improvements. The modeled cirrus cloud cover and IWC were by at least a factor of 2 higher in the relevant altitudes compared to the noninteractive model run. We attributed these improvements mainly to enhanced deposition freezing in response to the high mineral dust concentrations. This was corroborated further in a significant decrease in ice particle radii towards more realistic values, compared to in situ measurements from the ML-CIRRUS aircraft campaign. By testing different empirical ice nucleation parameterizations, we further demonstrate that remaining uncertainties in the ice-nucleating properties of mineral dust affect the model performance at least as significantly as including the online representation of the mineral dust distribution. Dust–radiation interactions played a secondary role for cirrus cloud formation, but contributed to a more realistic representation of precipitation by suppressing moist convection in southern Germany. In addition, a too-low specific humidity in the 7 to 10 km altitude range in the boundary conditions was identified as one of the main reasons for misrepresentation of cirrus clouds in this model study.

scholarly journals U.K. HiGEM: Impacts of Desert Dust Radiative Forcing in a High-Resolution Atmospheric GCM

2014 ◽  
Vol 27 (15) ◽  
pp. 5907-5928 ◽  
Author(s):  
M. J. Woodage ◽  
S. Woodward
Keyword(s):  
Particle Size ◽  
High Resolution ◽  
Particle Size Distribution ◽  
Size Distribution ◽  
Radiative Forcing ◽  
Mineral Dust ◽  
West African Monsoon ◽  
Radiative Properties ◽  
Saharan Dust ◽  
Dust Particles

Abstract This work investigates the impacts of mineral dust aerosol on climate using the atmospheric component of the U.K. High-Resolution Global Environmental Model (HiGEM) with an interactive embedded mineral dust scheme. It extends earlier work by Woodage et al. in which direct radiative forcing due to dust was calculated and in which it was reported that the global total dust burden was increased when this was included in the model. Here this result is analyzed further and the regional and global impacts are investigated. It is found that particle size distribution is critically important: In regions where large, more absorbent dust particles are present, burdens are increased because of the enhanced heating aloft, which strengthens convection, whereas, in areas where smaller, more scattering particles dominate, the surface layers are stabilized and dust emissions are decreased. The consequent changes in dust load and particle size distribution when radiative effects are included make the annual mean global forcing more positive at the top of the atmosphere (0.33 versus 0.05 W m−2). Impacts on the West African monsoon are also considered, where Saharan dust brings about a northward shift in the summertime intertropical convergence zone with increased precipitation on its northern side. This contrasts with results from some other studies, but the authors’ findings are supported by recent observational data. They argue that the impacts depend crucially on the size distribution and radiative properties of the dust particles, which are poorly known on a global scale and differ here from those used in other models.

scholarly journals The contribution of Saharan dust to the ice nucleating particle concentrations at the High Altitude Station Jungfraujoch (3580 m a.s.l.), Switzerland

2021 ◽  
Author(s):  
Cyril Brunner ◽  
Benjamin Tobias Brem ◽  
Martine Collaud Coen ◽  
Franz Conen ◽  
Maxime Hervo ◽  
...  
Keyword(s):  
High Altitude ◽  
Mineral Dust ◽  
Saharan Dust ◽  
Dust Particles ◽  
Ice Formation ◽  
Research Station ◽  
Backscatter Signal ◽  
Dust Mass ◽  
The Impact ◽  
Mass Concentrations

Abstract. The ice phase in mixed-phase clouds has a pivotal role in global precipitation formation as well as for Earth's radiative budget. Above 235 K, sparse particles with the special ability to initiate ice formation, ice nucleating particles (INPs), are responsible for primary ice formation within these clouds. However, the abundance and distribution of INPs remain largely unknown. Mineral dust is known to be the most abundant INP in the atmosphere at temperatures colder than 258 K. To better constrain and quantify the impact of mineral dust on ice nucleation, we investigate the frequency of Saharan dust events (SDEs) and their contribution to the INP number concentration at 243 K and at a saturation ratio with respect to liquid water (Sw) of 1.04 at the High Altitude Research Station Jungfraujoch (JFJ; 3580 m a.s.l.) from February to December 2020. Using the single scattering albedo Angström exponent, satellite retrieved dust mass concentrations, simulated tropospheric residence times, and the attenuated backscatter signal from a ceilometer as proxies, we detected 26 SDEs, which in total contributed to 17 % of the time span analyzed. We found every SDE to show an increase in median INP concentrations compared to that of all non-SDE periods, however, not always statistically significant. Median INP concentrations of individual SDEs spread between 1.7 and 161 INP std L−1, thus, two orders of magnitude. In the entire period analyzed, 74.7 ± 0.2 % of all INPs were measured during SDEs. Based on satellite retrieved dust mass concentrations, we argue that mineral dust is also present at the JFJ outside of SDEs, but at much lower concentrations, thus still contributing to the INP population. We estimate 97.0 ± 0.3 % of all INPs active in the immersion mode at 243 K Sw = 1.04 at the JFJ to be mineral dust particles. Overall, we found INP number concentrations to follow a leptokurtic log-normal frequency distribution. We found the INP number concentrations during SDEs to correlate with the ceilometer backscatter signals from a ceilometer located 4.5 km north of the JFJ and 1510 m lower in altitude, thus scanning the air masses at the same altitude as the JFJ. Using the European ceilometer network allows studying the atmospheric pathway of mineral dust plumes over a large domain, which we demonstrate in two case studies. These studies showed that mineral dust plumes form ice crystals at cirrus altitudes, which then sediment to lower altitudes. Upon sublimation in dryer air layers, the residual particles are left potentially pre-activated. Future improvements to the sampling lines of INP counters are required to study if these particles are indeed pre-activated, leading to larger INP number concentrations than reported here.

scholarly journals Impact of mineral dust on cloud formation in a Saharan outflow region

2012 ◽  
Vol 12 (23) ◽  
pp. 11383-11393 ◽  
Author(s):  
L. Smoydzin ◽  
A. Teller ◽  
H. Tost ◽  
M. Fnais ◽  
J. Lelieveld
Keyword(s):  
Radiative Forcing ◽  
Mineral Dust ◽  
Eastern Mediterranean ◽  
Cloud Condensation Nuclei ◽  
Coupled Model ◽  
Cloud Formation ◽  
Dust Particles ◽  
Ice Nuclei ◽  
Outflow Region ◽  
The Impact

Abstract. We present a numerical modelling study investigating the impact of mineral dust on cloud formation over the Eastern Mediterranean for two case studies: (i) 25 September 2008 and (ii) 28/29 January 2003. In both cases dust plumes crossed the Mediterranean and interacted with clouds forming along frontal systems. For our investigation we used the fully online coupled model WRF-chem. The results show that increased aerosol concentrations due to the presence of mineral dust can enhance the formation of ice crystals. This leads to slight shifts of the spatial and temporal precipitation patterns compared to scenarios where dust was not considered to act as ice nuclei. However, the total amount of precipitation did not change significantly. The only exception occurred when dust entered into an area of orographic ascent, causing glaciation of the clouds, leading to a local enhancement of rainfall. The impact of dust particles acting as giant cloud condensation nuclei on precipitation formation was found to be small. Based on our simulations the contribution of dust to the CCN population is potentially significant only for warm phase clouds. Nevertheless, the dust-induced differences in the microphysical structure of the clouds can contribute to a significant radiative forcing, which is important from a climate perspective.

scholarly journals The contribution of Saharan dust to the ice-nucleating particle concentrations at the High Altitude Station Jungfraujoch (3580 m a.s.l.), Switzerland

2021 ◽  
Vol 21 (23) ◽  
pp. 18029-18053
Author(s):  
Cyril Brunner ◽  
Benjamin T. Brem ◽  
Martine Collaud Coen ◽  
Franz Conen ◽  
Maxime Hervo ◽  
...  
Keyword(s):  
High Altitude ◽  
Mineral Dust ◽  
Saharan Dust ◽  
Dust Particles ◽  
Ice Formation ◽  
Research Station ◽  
Backscatter Signal ◽  
Dust Mass ◽  
The Impact ◽  
Mass Concentrations

Abstract. The ice phase in mixed-phase clouds has a pivotal role in global precipitation formation as well as for Earth's radiative budget. Above 235 K, sparse particles with the special ability to initiate ice formation, ice-nucleating particles (INPs), are responsible for primary ice formation within these clouds. Mineral dust has been found to be one of the most abundant INPs in the atmosphere at temperatures colder than 258 K. However, the extent of the abundance and distribution of INPs remains largely unknown. To better constrain and quantify the impact of mineral dust on ice nucleation, we investigate the frequency of Saharan dust events (SDEs) and their contribution to the INP number concentration at 243 K and at a saturation ratio with respect to liquid water (Sw) of 1.04 at the High Altitude Research Station Jungfraujoch (JFJ; 3580 m a.s.l.) from February to December 2020. Using the single-scattering albedo Ångström exponent retrieved from a nephelometer and an Aethalometer, satellite-retrieved dust mass concentrations, simulated tropospheric residence times, and the attenuated backscatter signal from a ceilometer as proxies, we detected 26 SDEs, which in total contributed to 17 % of the time span analyzed. We found every SDE to show an increase in median INP concentrations compared to those of all non-SDE periods; however, they were not always statistically significant. Median INP concentrations of individual SDEs spread between 1.7 and 161 INP std L−1 and thus 2 orders of magnitude. In the entire period analyzed, 74.7 ± 0.2 % of all INPs were measured during SDEs. Based on satellite-retrieved dust mass concentrations, we argue that mineral dust is also present at JFJ outside of SDEs but at much lower concentrations, thus still contributing to the INP population. We estimate that 97 % of all INPs active in the immersion mode at 243 K and Sw=1.04 at JFJ are dust particles. Overall, we found INP number concentrations to follow a leptokurtic lognormal frequency distribution. We found the INP number concentrations during SDEs to correlate with the ceilometer backscatter signals from a ceilometer located 4.5 km north of JFJ and 1510 m lower in altitude, thus scanning the air masses at the same altitude as JFJ. Using the European ceilometer network allows us to study the atmospheric pathway of mineral dust plumes over a large domain, which we demonstrate in two case studies. These studies showed that mineral dust plumes form ice crystals at cirrus altitudes, which then sediment to lower altitudes. Upon sublimation in dryer air layers, the residual particles are left potentially pre-activated. Future improvements to the sampling lines of INP counters are required to study whether these particles are indeed pre-activated, leading to larger INP number concentrations than reported here.

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

Minerals ◽  
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.

scholarly journals Modelling Atmospheric Mineral Aerosol Chemistry to Predict Heterogeneous Photooxidation of SO<sub>2</sub>

2017 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang ◽  
Jiyeon Park
Keyword(s):  
Mineral Dust ◽  
Uv Light ◽  
Full Range ◽  
Saharan Dust ◽  
Dust Particles ◽  
Oh Radicals ◽  
Desorption Kinetics ◽  
So2 Oxidation ◽  
Photocatalytic Ability ◽  
Sulfate Formation

Abstract. The photocatalytic ability of airborne mineral dust particles is known to heterogeneously promote SO2 oxidation, but prediction of this phenomenon is not fully taken into account by current models. In this study, the Atmospheric Mineral Aerosol Reaction (AMAR) model was developed to capture the influence of air-suspended mineral dust particles on sulfate formation in various environments. In the model, SO2 oxidation proceeds in three phases including the gas phase, the inorganic-salted aqueous phase (non-dust phase), and the dust phase. Dust chemistry is described as the adsorption-desorption kinetics (gas-particle partitioning) of SO2 and NOx. The reaction of adsorbed SO2 on dust particles occurs via two major paths: autoxidation of SO2 in open air and photocatalytic mechanisms under UV light. The kinetic mechanism of autoxidation was first leveraged using controlled indoor chamber data in the presence of Arizona Test Dust (ATD) particles without UV light, and then extended to photochemistry. With UV light, SO2 photooxidation was promoted by surface oxidants (OH radicals) that are generated via the photocatalysis of semiconducting metal oxides (electron–hole theory) of ATD particles. This photocatalytic rate constant was derived from the integration of the combinational product of the dust absorbance spectrum and wave-dependent actinic flux for the full range of wavelengths of the light source. The predicted concentrations of sulfate and nitrate using the AMAR model agreed well with outdoor chamber data that were produced under natural sunlight. For seven consecutive hours of photooxidation of SO2 in an outdoor chamber, dust chemistry at the low NOx level was attributed to 70 % of total sulfate (60 ppb SO2, 290 μg m−3 ATD, and NOx less than 5 ppb). At high NOx (> 50 ppb of NOx with low hydrocarbons), sulfate formation was also greatly promoted by dust chemistry, but it was significantly suppressed by the competition between NO2 and SO2 that both consume the dust-surface oxidants (OH radicals or ozone). The AMAR model, derived in this study with ATD particles, will provide a platform for predicting sulfate formation in the presence of authentic dust particles (e.g. Gobi and Saharan dust).

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