Tropospheric Mineral Dust Study by High Spectral Resolution Infrared Satellite during intense dust storms

Author(s):  
Perla Alalam ◽  
Hervé Herbin

<p>Large desert lands such as Sahara, Gobi or Australia present main sources of atmospheric mineral dust caused by intense dust storms. Transported dust particles undergo physical and chemical changes affecting their microphysical and optical properties. This modifies their scattering and absorption properties and alters the global atmospheric radiative budget.</p><p>Currently, remote sensing techniques represent a powerful tool for quantitative atmospheric measurements and the only means of analyzing its evolution from local to global scale. In order to improve the knowledge of atmospheric aerosol distributions, many efforts were made particularly in the development of hyperspectral infrared spectrometers and processing algorithms. However, to fully exploit these measurements, a perfect knowledge of Complex Refractive Index (CRI) is required.</p><p>In that purpose, a new methodology <sup></sup>based on laboratory measurements of mineral dust in suspension coupled with an optimal estimation method has been developed. This approach allows getting access to CRI of several desert samples with various chemical compositions.</p><p>Here, we present the first results of the physical parameters (effective radius and concentration) retrievals using Infrared Atmospheric Sounding Interferometer IASI data, during dust storm events. The latter use the CRI of different desert samples obtained in laboratory and a new radiative transfer algorithm (ARAHMIS) developed at Laboratoire d’Optique Atmosphérique LOA.</p>

2015 ◽  
Vol 15 (1) ◽  
pp. 393-409 ◽  
Author(s):  
P. J. DeMott ◽  
A. J. Prenni ◽  
G. R. McMeeking ◽  
R. C. Sullivan ◽  
M. D. Petters ◽  
...  

Abstract. Data from both laboratory studies and atmospheric measurements are used to develop an empirical parameterization for the immersion freezing activity of natural mineral dust particles. Measurements made with the Colorado State University (CSU) continuous flow diffusion chamber (CFDC) when processing mineral dust aerosols at a nominal 105% relative humidity with respect to water (RHw) are taken as a measure of the immersion freezing nucleation activity of particles. Ice active frozen fractions vs. temperature for dusts representative of Saharan and Asian desert sources were consistent with similar measurements in atmospheric dust plumes for a limited set of comparisons available. The parameterization developed follows the form of one suggested previously for atmospheric particles of non-specific composition in quantifying ice nucleating particle concentrations as functions of temperature and the total number concentration of particles larger than 0.5 μm diameter. Such an approach does not explicitly account for surface area and time dependencies for ice nucleation, but sufficiently encapsulates the activation properties for potential use in regional and global modeling simulations, and possible application in developing remote sensing retrievals for ice nucleating particles. A calibration factor is introduced to account for the apparent underestimate (by approximately 3, on average) of the immersion freezing fraction of mineral dust particles for CSU CFDC data processed at an RHw of 105% vs. maximum fractions active at higher RHw. Instrumental factors that affect activation behavior vs. RHw in CFDC instruments remain to be fully explored in future studies. Nevertheless, the use of this calibration factor is supported by comparison to ice activation data obtained for the same aerosols from Aerosol Interactions and Dynamics of the Atmosphere (AIDA) expansion chamber cloud parcel experiments. Further comparison of the new parameterization, including calibration correction, to predictions of the immersion freezing surface active site density parameterization for mineral dust particles, developed separately from AIDA experimental data alone, shows excellent agreement for data collected in a descent through a Saharan aerosol layer. These studies support the utility of laboratory measurements to obtain atmospherically relevant data on the ice nucleation properties of dust and other particle types, and suggest the suitability of considering all mineral dust as a single type of ice nucleating particle as a useful first-order approximation in numerical modeling investigations.


2019 ◽  
Vol 19 (1) ◽  
pp. 219-232 ◽  
Author(s):  
Xiaole Pan ◽  
Baozhu Ge ◽  
Zhe Wang ◽  
Yu Tian ◽  
Hang Liu ◽  
...  

Abstract. Depolarization ratio (δ) of backscattered light is an applicable parameter for distinguishing the sphericity of particles in real time, which has been widely adopted by ground-based lidar observation systems. In this study, δ values of particles and chemical compositions in both PM2.5 (aerodynamic diameter less than 2.5 µm) and PM10 (aerodynamic diameter less than 10 µm) were concurrently measured on the basis of a bench-top optical particle counter with a polarization detection module (POPC) and a continuous dichotomous aerosol chemical speciation analyzer (ACSA-14) from November 2016 to February 2017 at an urban site in Beijing megacity. In general, measured δ values depended on both size and sphericity of the particles. During the observation period, mass concentrations of NO3- in PM2.5 (fNO3) were about an order of magnitude higher than that in PM2.5−10 (cNO3) with a mean fNO3∕cNO3 ratio of 14±10. A relatively low fNO3∕cNO3 ratio (∼5) was also observed under higher relative humidity conditions, mostly due to heterogeneous processes and particles in the coarse mode. We found that δ values of ambient particles in both PM2.5 and PM2.5−10 obviously decreased as mass concentration of water-soluble species increased at unfavorable meteorological conditions. This indicated that the morphology of particles was changed as a result of water-absorbing processes. The particles with optical size (Dp) of Dp = 5 µm were used to represent mineral dust particles, and its δ values (δDp=5) decreased by 50 % as the mass fraction of cNO3 increased from 2 % to 8 % and ambient relative humidity increased up to 80 %, suggesting that mineral dust particles were likely to be spherical during humid pollution episodes. During the observation, relative humidity inside the POPC measuring chamber was stable at 34±2 %, lower than the ambient condition. Its influence on the morphology was estimated to be limited and did not change our major conclusion. This study highlights the evident alteration of non-sphericity of mineral dust particles during their transport owing to a synergistic effect of both pollutant coatings and hygroscopic processes, which plays an important role in the evaluation of its environmental effect.


2020 ◽  
Author(s):  
Eyal Ben Dor ◽  
Gila Notesko ◽  
Shahar Weksler

<p>Soil mineralogy holds important information on the soil origin and development. Most common minerals in soils—quartz, clay minerals and carbonates—present fundamental spectral features in the longwave infrared (LWIR) region (8.0–12 μm range), whereas quartz is featureless in the optical region (0.4–2.5 μm range). A procedure for determining the soil surface mineralogy from hyperspectral LWIR data was used to assess the interaction with desert dust particles that accumulate on the soil surface during dust storms. Ground- and field-based hyperspectral LWIR images of different types of Israeli soils, before and after dispersion of desert dust-like material on the surface, were acquired with the Telops Hyper-Cam sensor, to calculate the surface emissivity spectra of soils, representing the surface mineralogy. Identifying mineral-related emissivity features and calculating their relative intensities, using two created indices―SQCMI (Soil Quartz Clay Mineral Index) and SCI (Soil Carbonate Index)―enabled determining the content of quartz, clay minerals, and carbonates in the soil in a semi-quantitative manner—from more to less abundant, and identifying changes in their abundance resulting from the dispersion of dust on the surface. The dust affected the mineral-related spectral features of the soil surface, depending on the mineral composition of the dust compared to soil surface mineralogy, and its amount. The ability to detect minor mineralogical changes on the soil surface using high spectral resolution LWIR data was demonstrated.</p>


2010 ◽  
Vol 10 (22) ◽  
pp. 10771-10788 ◽  
Author(s):  
T. Stanelle ◽  
B. Vogel ◽  
H. Vogel ◽  
D. Bäumer ◽  
C. Kottmeier

Abstract. We used the comprehensive model system COSMO-ART to quantify the impact of mineral dust on the radiative fluxes, the temperature and the feedback between dust particles and their emissions. We simulated two dust storms over West Africa in March 2006 and in June 2007. Simulations with and without coupling of the actual dust concentration with the radiative fluxes and the thermodynamics were carried out for each case. The model results for the 2006 case were compared with observations of the AMMA campaign. At the surface the shortwave radiative effect of mineral dust can be described by a linear relation between the changes in net surface radiation and the aerosol optical depth (AOD). For an AOD at 450 nm of 1 the average shortwave radiation reduction amounts −140 W m−2 during noon. The longwave radiative effect of mineral dust is nonlinear, with an average increase of +70 W m−2 for an AOD (450 nm) of 1. At the top of the atmosphere the effect of the dust layer with an AOD of 1 on radiative fluxes is not as significant as at the surface. It is slightly positive for the shortwave and approximately 26 W m−2 for the longwave radiation. The height range and the extension of the dust layer determine the effect of dust particles on the 2 m temperature. When the dust layer is attached to the surface and lasts for several days it leads to an increase of the surface temperature even during daytime. In case of an elevated dust layer there is a decrease in 2 m temperature of up to 4 K during noon. It is shown, that the temperature changes caused by mineral dust may result in horizontal temperature gradients which also modify near surface winds. Since surface wind thresholds decide the uptake of dust from the surface, a feedback on total emission fluxes is established. The coupled model provides an increase in the total emission fluxes of dust particles by about 16% during the dust storm in March 2006 and 25% during the dust episode in June 2007.


2021 ◽  
Author(s):  
Alain Miffre ◽  
Danaël Cholleton ◽  
Patrick Rairoux

<p>This abstract is dedicated to dual-wavelength polarization lidars (2β+2δ) and related particles backscattering Ångström exponents BAE<sub>p</sub>, as nowadays remotely evaluated by atmospheric multi-wavelength lidar instruments (Veselovskii et al., ACP, 2016). We here present two new lidar remote sensing developments applicable to every multi-wavelengths polarization lidars, as published in Miffre et al. (Rem. Sens. 2019, Opt. Lett. 2020).</p><p>As a first development, we investigate the size, shape and complex refractive index dependence of measured backscattering Ångström exponents (Miffre et al., Opt. Lett., 2020). If BAE<sub>p</sub> is generally considered as a particles size indicator, it actually depends on the particles size, shape (Mehri et al., Atm. Res., 2018) and complex refractive index as β<sub>p</sub> does. From a precise analysis of the polarization state of the backscattered radiation and of its wavelength dependence, in two components particle mixtures (p) = {s, ns} involving spherical (s) and nonspherical (ns)-particles, we could establish the relationship between BAE<sub>p</sub>, BAE<sub>s</sub> and BAE<sub>ns</sub>. Then, by numerically simulating the two latter, we could discuss on the range of involved particle sizes and complex refractive indices.</p><p>The second development is related to the remote sensing observation of a new particle formation event with a dual-wavelength polarization lidar (Miffre et al. Rem. Sens. 2019). Where previous thoughts were that it is not feasible due to the small size of involved particles, we identified the requirements ensuring a (UV, VIS) polarization lidar to be sensitive to the subsequent particles growth following nucleation events promoted by nonspherical mineral dust particles. The presentation will explicit these optical requirements in terms of polarization and spectroscopy, as recently published in (Miffre et al., Rem. Sens., 2019).</p><p>The oral presentation will first present our dual-wavelength polarization lidar remote sensing instrument (2β+2δ), based on an unique laboratory Pi-polarimeter (Miffre et al., JQSRT, 2016). Special focus will be made on the (UV, VIS) calibration of the polarization lidar, as a decisive point for precise observations and interpretations. As an application case study, the oral presentation will then consider the lidar remote sensing observation of a nucleation event promoted by mineral dust. There, the involved particles sizes of freshly nucleated sulfuric acid particles and mineral dust will be retrieved by considering the above backscattering Ångström exponents analysis. As expected, the retrieved involved particles sizes reveal the underlying physical-chemistry of the nucleation process promoted by mineral dust (Dupart et al., PNAS, 2012). We believe this work may then interest a wide community of scientists.</p><p>Veselovskii, I., P. Goloub, D. N. Whiteman, A. Diallo, T. Ndiaye, A. Kolgotin, and O. Dubovik, ACP, <strong>16</strong>(11), (2016).<br>Dupart, Y., A. Wiedensohler, H. Hermann, A. Miffre, P. Rairoux, B. D’Anna and C. George, PNAS, 109, 51, (2012).<br>Miffre, A., T. Mehri, M. Francis and P. Rairoux, JQSRT, 169, 79-90, (2016).<br>Mehri, T., P. Rairoux, T. Nousiainen, A. Miffre, Atm. Res. <strong>203</strong>, 44-61 (2018).<br>Miffre A, D Cholleton, T. Mehri and P Rairoux, Rem. Sens., 11(15), 1761, (2019).<br>Miffre, A., D. Cholleton, P. Rairoux, Opt. Lett.<strong> 45</strong>, 5, 1084-1087, (2020).</p>


2014 ◽  
Vol 14 (7) ◽  
pp. 3307-3323 ◽  
Author(s):  
H. Geng ◽  
H. Hwang ◽  
X. Liu ◽  
S. Dong ◽  
C.-U. Ro

Abstract. This is the first study of Asian dust storm (ADS) particles collected in Beijing, China, and Incheon, Korea, during a spring ADS event. Using a seven-stage May impactor and a quantitative electron probe X-ray microanalysis (ED-EPMA, also known as low-Z particle EPMA), we examined the composition and morphology of 4200 aerosol particles at stages 1–6 (with a size cut-off of 16, 8, 4, 2, 1, and 0.5 μm in equivalent aerodynamic diameter, respectively) collected during an ADS event on 28–29 April 2005. The results showed that there were large differences in the chemical compositions between particles in sample S1 collected in Beijing immediately after the peak time of the ADS and in samples S2 and S3, which were collected in Incheon approximately 5 h and 24 h later, respectively. In sample S1, mineral dust particles accounted for more than 88% in relative number abundance at stages 1–5; and organic carbon (OC) and reacted NaCl-containing particles accounted for 24% and 32%, respectively, at stage 6. On the other hand, in samples S2 and S3, in addition to approximately 60% mineral dust, many sea spray aerosol (SSA) particles reacted with airborne SO2 and NOx (accounting for 24% and 14% on average in samples S2 and S3, respectively), often mixed with mineral dust, were encountered at stages 1–5, and (C, N, O, S)-rich particles (likely a mixture of water-soluble organic carbon with (NH4)2SO4 and NH4NO3) were abundantly observed at stage 6 (accounting for 68% and 51% in samples S2 and S3, respectively). This suggests that an accumulation of sea-salt components on individual ADS particles larger than 1 μm in diameter occurred and many secondary aerosols smaller than 1 μm in diameter were formed when the ADS particles passed over the Yellow Sea. In the reacted or aged mineral dust and SSA particles, nitrate-containing and both nitrate- and sulfate-containing species vastly outnumbered the sulfate-containing species, implying that ambient NOx had a greater influence on the atmospheric particles than SO2 during this ADS episode. In addition to partially- or totally-reacted CaCO3, reacted or aged Mg-containing aluminosilicates were observed frequently in samples S2 and S3; furthermore, a student's t test showed that both their atomic concentration ratios of [Mg] / [Al] and [Mg] / [Si] were significantly elevated (P < 0.05) compared to those in samples S1 (for [Mg] / [Al], 0.34 ± 0.09 and 0.40 ± 0.03 in samples S2 and S3, respectively, vs. 0.24 ± 0.01 in sample S1; for [Mg] / [Si], 0.21 ± 0.05 and 0.22 ± 0.01 in samples S2 and S3, respectively, vs. 0.12 ± 0.02 in sample S1). The significant increase of [Mg] / [Al] and [Mg] / [Si] ratios in Mg-containing aluminosilicates indicates that a significant evolution or aging must have occurred on the ADS particles in the marine atmosphere during transport from China to Korea.


2020 ◽  
Vol 267 ◽  
pp. 115338
Author(s):  
Vikas Goel ◽  
Sumit K. Mishra ◽  
Prabir Pal ◽  
Ajit Ahlawat ◽  
Narayanasamy Vijayan ◽  
...  

2020 ◽  
pp. 1-15
Author(s):  
Anca Nemuc ◽  
Sara Basart ◽  
Aurelio Tobias ◽  
Slobodan Nickovic ◽  
Francesca Barnaba ◽  
...  

Amongst the most significant extreme meteorological phenomena are the Sand and Dust Storms (SDS). Owing to significant amounts of airborne mineral dust particles generated during these events, SDS have impacts on climate, the environment, human health, and many socio-economic sectors (e.g. aviation, solar energy management). Many studies and reports have underlined that the society has to understand, manage and mitigate the risks and effects of SDS on life, health, property, the environment and the economy in a more unified way. The EU-funded European Cooperation in Science and Technology (COST) Action ‘InDust: International network to encourage the use of monitoring and forecasting Dust products’ has an overall objective to establish a network involving research institutions, service providers and potential end users on airborne dust information. We are a multidisciplinary group of international experts on aerosol measurements, aerosol modelling, stakeholders and social scientists working together, exchanging ideas to better coordinate and harmonize the process of transferring dust observation and prediction data to users, as well as to assist the diverse socio-economic sectors affected by the presence of high concentrations of airborne mineral dust. This article highlights the importance of being actively engaged in research networking activities, supported by EU and COST actions since common efforts help not only each scientist by shaping their expertise and strengthening their position, but also all communities.


2010 ◽  
Vol 7 (2) ◽  
pp. 162 ◽  
Author(s):  
Juan G. Navea ◽  
Haihan Chen ◽  
Min Huang ◽  
Gregory R. Carmichel ◽  
Vicki H. Grassian

Environmental context. Dust particles produced from wind blown soils are of global significance as these dust particles not only impact visibility, as evident in the recent 2009 Australian dust storm, but also atmospheric chemistry, climate and biogeochemical cycles. The amount of water vapour in the atmosphere (relative humidity) can play a role in these global processes yet there are few studies and little quantitative data on water-dust particle interactions. The focus of this research is on quantifying water-dust particle interactions for several dust sources including Asia and Africa where dust storms are most prevalent. Abstract. Mineral dust aerosol provides a reactive surface in the troposphere. The reactivity of mineral dust depends on the source region as chemical composition and mineralogy of the aerosol affects its interaction with atmospheric gases. Furthermore, the impact of mineral dust aerosol in atmospheric processes and climate is a function of relative humidity. In this study, we have investigated water uptake of complex dust samples. In particular, water uptake as a function of relative humidity has been measured on three different dust sources that have been characterised using a variety of bulk and surface techniques. For these well-characterised dust samples, it is shown that although there are variations in chemical composition and mineralogy, on a per mass basis, water uptake capacities for the three dusts are very similar and are comparable to single component clay samples. These results suggest that the measured uptake of water of these bulk samples is dominated by the clay component.


2007 ◽  
Vol 7 (1) ◽  
pp. 2133-2168
Author(s):  
G. Fratini ◽  
P. Ciccioli ◽  
A. Febo ◽  
A. Forgione ◽  
R. Valentini

Abstract. Mineral dust emission accounts for a substantial portion of particles present in the troposphere. It is emitted most from desert areas, mainly through intense storm episodes. The aim of this work was to quantify size-segregated fluxes of mineral dust particles emitted during storm events occurring in desert areas of northern China (Alashan desert, Inner Mongolia), known to act as one of the strongest sources of mineral dust particles in the Asian continent. Long-range transport of mineral dust emitted in this area is responsible for the high particle concentrations reached in densely populated areas, including the city of Beijing. Based on a theoretical analysis, an eddy covariance system was built to get size-segregated fluxes of mineral dust particles with optical diameters ranging between 0.26 and 7.00 μm. The system was optimised to measure fluxes under intense storm event conditions. It was tested in two sites located in the Chinese portion of the Gobi desert. During the field campaign, an intense storm event was recorded in one of them. Data obtained during this event indicate that particle number fluxes were dominated by the finer fraction, whereas in terms of volume, coarser particle accounted for the largest portion. It was found that during the storm event, ratios of size-segregated particle volume fluxes remained substantially constant and a simple parameterization of particle emission from total volume fluxes was possible. A strong correlation was also found between particle volume fluxes and the friction velocity. This relationship is extremely useful to investigate mechanisms of particle formation by wind erosion.


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