Effect of superfine KHCO3 and ABC powder on ignition sensitivity of PMMA dust layer

We report on a long-lasting (10 days) Saharan dust event affecting large sections of South-Eastern Europe by using a synergy of lidar, satellite, in-situ observations and model simulations over Athens, Greece. The dust measurements (11–20 May 2020), performed during the confinement period due to the COVID-19 pandemic, revealed interesting features of the aerosol dust properties in the absence of important air pollution sources over the European continent. During the event, moderate aerosol optical depth (AOD) values (0.3–0.4) were observed inside the dust layer by the ground-based lidar measurements (at 532 nm). Vertical profiles of the lidar ratio and the particle linear depolarization ratio (at 355 nm) showed mean layer values of the order of 47 ± 9 sr and 28 ± 5%, respectively, revealing the coarse non-spherical mode of the probed plume. The values reported here are very close to pure dust measurements performed during dedicated campaigns in the African continent. By utilizing Libradtran simulations for two scenarios (one for typical midlatitude atmospheric conditions and one having reduced atmospheric pollutants due to COVID-19 restrictions, both affected by a free tropospheric dust layer), we revealed negligible differences in terms of radiative effect, of the order of +2.6% (SWBOA, cooling behavior) and +1.9% (LWBOA, heating behavior). Moreover, the net heating rate (HR) at the bottom of the atmosphere (BOA) was equal to +0.156 K/d and equal to +2.543 K/d within 1–6 km due to the presence of the dust layer at that height. On the contrary, the reduction in atmospheric pollutants could lead to a negative HR (−0.036 K/d) at the bottom of the atmosphere (BOA) if dust aerosols were absent, while typical atmospheric conditions are estimated to have an almost zero net HR value (+0.006 K/d). The NMMB-BSC forecast model provided the dust mass concentration over Athens, while the air mass advection from the African to the European continent was simulated by the Hybrid Single-Particle Lagrangian Integrated Trajectory (HYSPLIT) model.

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EARLINET dust observations vs. BSC-DREAM8b modeled profiles: 12-year-long systematic comparison at Potenza, Italy

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-8781-2014 ◽

2014 ◽

Vol 14 (16) ◽

pp. 8781-8793 ◽

Cited By ~ 39

Author(s):

L. Mona ◽

N. Papagiannopoulos ◽

S. Basart ◽

J. Baldasano ◽

I. Binietoglou ◽

...

Keyword(s):

Center Of Mass ◽

Saharan Dust ◽

Raman Lidar ◽

Dust Layer ◽

Systematic Comparison ◽

Dust Extinction ◽

Lidar Measurements ◽

Order Of Magnitude ◽

Lidar Ratio ◽

532 Nm

Abstract. In this paper, we report the first systematic comparison of 12-year modeled dust extinction profiles vs. Raman lidar measurements. We use the BSC-DREAM8b model, one of the most widely used dust regional models in the Mediterranean, and Potenza EARLINET lidar profiles for Saharan dust cases, the largest one-site database of dust extinction profiles. A total of 310 dust cases were compared for the May 2000–July 2012 period. The model reconstructs the measured layers well: profiles are correlated within 5% of significance for 60% of the cases and the dust layer center of mass as measured by lidar and modeled by BSC-DREAM8b differ on average 0.3 ± 1.0 km. Events with a dust optical depth lower than 0.1 account for 70% of uncorrelated profiles. Although there is good agreement in terms of profile shape and the order of magnitude of extinction values, the model overestimates the occurrence of dust layer top above 10 km. Comparison with extinction profiles measured by the Raman lidar shows that BSC-DREAM8b typically underestimates the dust extinction coefficient, in particular below 3 km. Lowest model–observation differences (below 17%) correspond to a lidar ratio at 532 nm and Ångström exponent at 355/532 nm of 60 ± 13 and 0.1 ± 0.6 sr, respectively. These are in agreement with values typically observed and modeled for pure desert dust. However, the highest differences (higher than 85%) are typically related to greater Ångström values (0.5 ± 0.6), denoting smaller particles. All these aspects indicate that the level of agreement decreases with an increase in mixing/modification processes.

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Aerosol's optical and physical characteristics and direct radiative forcing during a shamal dust storm, a case study

Atmospheric Chemistry and Physics ◽

10.5194/acp-14-3751-2014 ◽

2014 ◽

Vol 14 (7) ◽

pp. 3751-3769 ◽

Cited By ~ 21

Author(s):

T. M. Saeed ◽

H. Al-Dashti ◽

C. Spyrou

Keyword(s):

Optical Thickness ◽

Dust Storm ◽

Radiative Forcing ◽

Longwave Radiation ◽

Aerosol Optical Thickness ◽

Radiative Heating ◽

Dust Layer ◽

Surface Level ◽

Maximum Value ◽

Direct Radiative Forcing

Abstract. Dust aerosols are analyzed for their optical and physical properties during an episode of a dust storm that blew over Kuwait on 26 March 2003 when the military Operation Iraqi Freedom was in full swing. The intensity of the dust storm was such that it left a thick suspension of dust throughout the following day, 27 March. The synoptic sequence leading to the dust storm and the associated wind fields are discussed. Ground-based measurements of aerosol optical thickness reached 3.617 and 4.17 on 26 and 27 March respectively while the Ångstrom coefficient, α870/440, dropped to −0.0234 and −0.0318. Particulate matter concentration of 10 μm diameter or less, PM10, peaked at 4800 μg m−3 during dust storm hours of 26 March. Moderate Resolution Imaging Spectroradiometer (MODIS) retrieved aerosol optical depth (AOD) by Deep Blue algorithm and Total Ozone Mapping Spectrometer (TOMS) aerosol index (AI) exhibited high values. Latitude–longitude maps of AOD and AI were used to deduce source regions of dust transport over Kuwait. The vertical profile of the dust layer was simulated using the SKIRON atmospheric model. Instantaneous net direct radiative forcing is calculated at top of atmosphere (TOA) and surface level. The thick dust layer of 26 March resulted in cooling the TOA by −60 Wm−2 and surface level by −175 Wm−2 for a surface albedo of 0.35. Slightly higher values were obtained for 27 March due to the increase in aerosol optical thickness. Radiative heating/cooling rates in the shortwave and longwave bands were also examined. Shortwave heating rate reached a maximum value of 2 K day−1 between 3 and 5 km, dropped to 1.5 K day−1 at 6 km and diminished at 8 km. Longwave radiation initially heated the lower atmosphere by a maximum value of 0.2 K day−1 at surface level, declined sharply at increasing altitude and diminished at 4 km. Above 4 km longwave radiation started to cool the atmosphere slightly reaching a maximum rate of −0.1 K day−1 at 6 km.

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Wave processes occuring in supersonic motion of blunted body through dust layer

10.1063/1.39459 ◽

1990 ◽

Author(s):

V. L. Belousov ◽

M. S. Ramm ◽

A. A. Schmidt

Keyword(s):

Wave Processes ◽

Dust Layer ◽

Blunted Body ◽

Supersonic Motion

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Observations of the spectral dependence of linear particle depolarization ratio of aerosols using NASA Langley airborne High Spectral Resolution Lidar

Atmospheric Chemistry and Physics ◽

10.5194/acp-15-13453-2015 ◽

2015 ◽

Vol 15 (23) ◽

pp. 13453-13473 ◽

Cited By ~ 87

Author(s):

S. P. Burton ◽

J. W. Hair ◽

M. Kahnert ◽

R. A. Ferrare ◽

C. A. Hostetler ◽

...

Keyword(s):

Case Studies ◽

Spectral Resolution ◽

Spectral Dependence ◽

Saharan Dust ◽

Spherical Particles ◽

High Spectral Resolution ◽

Depolarization Ratio ◽

Dust Layer ◽

High Spectral Resolution Lidar ◽

532 Nm

Abstract. Linear particle depolarization ratio is presented for three case studies from the NASA Langley airborne High Spectral Resolution Lidar-2 HSRL-2). Particle depolarization ratio from lidar is an indicator of non-spherical particles and is sensitive to the fraction of non-spherical particles and their size. The HSRL-2 instrument measures depolarization at three wavelengths: 355, 532, and 1064 nm. The three measurement cases presented here include two cases of dust-dominated aerosol and one case of smoke aerosol. These cases have partial analogs in earlier HSRL-1 depolarization measurements at 532 and 1064 nm and in literature, but the availability of three wavelengths gives additional insight into different scenarios for non-spherical particles in the atmosphere. A case of transported Saharan dust has a spectral dependence with a peak of 0.30 at 532 nm with smaller particle depolarization ratios of 0.27 and 0.25 at 1064 and 355 nm, respectively. A case of aerosol containing locally generated wind-blown North American dust has a maximum of 0.38 at 1064 nm, decreasing to 0.37 and 0.24 at 532 and 355 nm, respectively. The cause of the maximum at 1064 nm is inferred to be very large particles that have not settled out of the dust layer. The smoke layer has the opposite spectral dependence, with the peak of 0.24 at 355 nm, decreasing to 0.09 and 0.02 at 532 and 1064 nm, respectively. The depolarization in the smoke case may be explained by the presence of coated soot aggregates. We note that in these specific case studies, the linear particle depolarization ratio for smoke and dust-dominated aerosol are more similar at 355 nm than at 532 nm, having possible implications for using the particle depolarization ratio at a single wavelength for aerosol typing.

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Gravitational instability in the dust layer of a protoplanetary disk: Interaction of solid particles with turbulent gas in the layer

Solar System Research ◽

10.1134/s0038094616060071 ◽

2016 ◽

Vol 50 (6) ◽

pp. 408-425 ◽

Cited By ~ 10

Author(s):

I. N. Ziglina ◽

A. B. Makalkin

Keyword(s):

Gravitational Instability ◽

Protoplanetary Disk ◽

Solid Particles ◽

Dust Layer

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Smoldering combustion of dust layer on hot surface

Journal of Loss Prevention in the Process Industries ◽

10.1016/s0950-4230(00)00004-8 ◽

2000 ◽

Vol 13 (6) ◽

pp. 509-517 ◽

Cited By ~ 9

Author(s):

Saad A El-Sayed ◽

Ahmed M Abdel-Latif

Keyword(s):

Dust Layer ◽

Smoldering Combustion ◽

Hot Surface

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Saharan dust infrared optical depth and altitude retrieved from AIRS: a focus over North Atlantic – comparison to MODIS and CALIPSO

Atmospheric Chemistry and Physics ◽

10.5194/acp-10-1953-2010 ◽

2010 ◽

Vol 10 (4) ◽

pp. 1953-1967 ◽

Cited By ~ 61

Author(s):

S. Peyridieu ◽

A. Chédin ◽

D. Tanré ◽

V. Capelle ◽

C. Pierangelo ◽

...

Keyword(s):

Optical Depth ◽

North Atlantic ◽

Western Indian Ocean ◽

Saharan Dust ◽

Orthogonal Polarization ◽

Dust Layer ◽

The North ◽

Moderate Resolution Imaging Spectroradiometer ◽

Good Agreement

Abstract. Monthly mean infrared (10 μm) dust layer aerosol optical depth (AOD) and mean altitude are simultaneously retrieved over the tropics (30° S–30° N) from almost seven years of Atmospheric Infrared Sounder (AIRS) observations covering the period January 2003 to September 2009. The method developed relies on the construction of look-up-tables computed for a large selection of atmospheric situations and follows two main steps: first, determination of the observed atmospheric thermodynamic situation and, second, determination of the dust properties. A very good agreement is found between AIRS-retrieved AODs and visible optical depths from the Moderate resolution Imaging Spectroradiometer (MODIS/Aqua) during the main (summer) dust season, in particular for three regions of the tropical North Atlantic and one region of the north-western Indian Ocean. Outside this season, differences are mostly due to the sensitivity of MODIS to aerosol species other than dust and to the more specific sensitivity of AIRS to the dust coarse mode. AIRS-retrieved dust layer mean altitudes are compared to the Cloud-Aerosol Lidar with Orthogonal Polarization (CALIOP/CALIPSO) aerosol mean layer altitude for the period June 2006 to June 2009. Results for a region of the north tropical Atlantic downwind of the Sahara show a good agreement between the two products (σ≈360 m). Differences observed in the peak-to-trough seasonal amplitude, smaller from AIRS, are principally attributed to the large difference in spatial sampling of the two instruments. They also come from the intrinsic limit in sensitivity of the passive infrared sounders for low altitudes. These results demonstrate the capability of high resolution infrared sounders to measure not only dust aerosol AOD but also the mean dust layer altitude.

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